U.S. patent application number 16/833265 was filed with the patent office on 2020-10-01 for method and apparatus for repetition-based data transmission for network cooperative communication.
The applicant listed for this patent is Samsung Electronics Co., Ltd.. Invention is credited to Taehan BAE, Hyoungju JI, Jinkyu KANG, Hoondong NOH, Jinhyun PARK, Heecheol YANG.
Application Number | 20200313796 16/833265 |
Document ID | / |
Family ID | 1000004767233 |
Filed Date | 2020-10-01 |
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United States Patent
Application |
20200313796 |
Kind Code |
A1 |
PARK; Jinhyun ; et
al. |
October 1, 2020 |
METHOD AND APPARATUS FOR REPETITION-BASED DATA TRANSMISSION FOR
NETWORK COOPERATIVE COMMUNICATION
Abstract
A method by a user equipment (UE) in a wireless communication
system includes: receiving a first physical downlink shared channel
(PDSCH) transmission and a second PDSCH transmission that carry a
same transport block (TB) and are associated with a first
transmission configuration indicator (TCI) state and a second TCI
state, respectively; determining a transport block size (TBS) of
the first PDSCH transmission; and determining low-density
parity-check (LDPC) base graph corresponding to the transport block
based on the determined TBS for each of the first PDSCH
transmission and the second PDSCH transmission, wherein the
determined TBS of the first PDSCH transmission is applied to the
second PDSCH transmission.
Inventors: |
PARK; Jinhyun; (Suwon-si,
KR) ; NOH; Hoondong; (Suwon-si, KR) ; KANG;
Jinkyu; (Suwon-si, KR) ; BAE; Taehan;
(Suwon-si, KR) ; YANG; Heecheol; (Suwon-si,
KR) ; JI; Hyoungju; (Suwon-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samsung Electronics Co., Ltd. |
Suwon-si |
|
KR |
|
|
Family ID: |
1000004767233 |
Appl. No.: |
16/833265 |
Filed: |
March 27, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04L 1/0057 20130101;
H04B 7/024 20130101; H04L 5/001 20130101; H04L 1/0027 20130101;
H04L 5/0094 20130101; H04L 1/0031 20130101; H04L 5/0035 20130101;
H04L 1/0038 20130101; H04L 5/0044 20130101 |
International
Class: |
H04L 1/00 20060101
H04L001/00; H04B 7/024 20060101 H04B007/024; H04L 5/00 20060101
H04L005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2019 |
KR |
10-2019-0037314 |
May 3, 2019 |
KR |
10-2019-0052384 |
Sep 6, 2019 |
KR |
10-2019-0110942 |
Claims
1. A method by a user equipment (UE) in a wireless communication
system, the method comprising: receiving a first physical downlink
shared channel (PDSCH) transmission and a second PDSCH transmission
that are associated with a first transmission configuration
indicator (TCI) state and a second TCI state, respectively, carry a
same transport block (TB); determining a first transport block size
(TBS) of the first PDSCH transmission, wherein the determined first
TBS is applied to a second TBS of the second PDSCH transmission;
and identifying, corresponding to the same transport block, a first
low-density parity-check (LDPC) base graph for the first TBS
transmission based on the determined first TBS and a second LDPC
base graph for the second TBS transmission based on the second
TBS.
2. The method of claim 1, wherein the first TCI state and the
second TCI state are indicated in downlink control information
(DCI).
3. The method of claim 1, wherein first frequency resources for the
first PDSCH transmission and second frequency resources for the
second PDSCH transmission do not overlap each other.
4. The method of claim 3, wherein the first PDSCH transmission and
the second PDSCH transmission are performed on same time
resources.
5. The method of claim 1, wherein a number of first resource
elements allocated to the first PDSCH transmission is greater than
or equal to a number of second resource elements allocated to the
second PDSCH transmission.
6. The method of claim 1, wherein the first PDSCH transmission
includes a lowest resource block among resource blocks allocated to
the first PDSCH transmission and the second PDSCH transmission.
7. The method of claim 1, further comprising determining a first
modulation order of the first PDSCH transmission, wherein the
determined first modulation order of the first PDSCH transmission
is applied to a second modulation order of the second PDSCH
transmission.
8. The method of claim 1, wherein the first PDSCH transmission and
the second PDSCH transmission are scheduled with a same number of
transmission layers in DCI.
9. A user equipment (UE) in a wireless communication system, the UE
comprising: a transceiver; and at least one processor coupled with
the transceiver and configured to: receive a first physical
downlink shared channel (PDSCH) transmission and a second PDSCH
transmission that are associated with a first transmission
configuration indicator (TCI) state and a second TCI state,
respectively, carry a same transport block (TB); determine a first
transport block size (TBS) of the first PDSCH transmission, wherein
the determined first TBS is applied to a second TBS of the second
PDSCH transmission; and identify, corresponding to the same
transport block, a first low-density parity-check (LDPC) base graph
for the first TBS transmission based on the determined first TBS
and a second LDPC base graph for the second TBS transmission based
on the second TBS.
10. The UE of claim 9, wherein the first TCI state and the second
TCI state are indicated in downlink control information (DCI).
11. The UE of claim 9, wherein first frequency resources for the
first PDSCH transmission and second frequency resources for the
second PDSCH transmission do not overlap each other.
12. The UE of claim 11, wherein the first PDSCH transmission and
the second PDSCH transmission are performed on same time
resources.
13. The UE of claim 9, wherein a number of first resource elements
allocated to the first PDSCH transmission is greater than or equal
to a number of second resource elements allocated to the second
PDSCH transmission.
14. The UE of claim 9, wherein the first PDSCH transmission
includes a lowest resource block among resource blocks allocated to
the first PDSCH transmission and the second PDSCH transmission.
15. The UE of claim 9, wherein the at least one processor is
further configured to determine a first modulation order of the
first PDSCH transmission, and wherein the determined first
modulation order of the first PDSCH transmission is applied to a
second modulation order of the second PDSCH transmission.
16. The UE of claim 9, wherein the first PDSCH transmission and the
second PDSCH transmission are scheduled with a same number of
transmission layers in DCI.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is based on and claims priority under 35
U.S.C. .sctn. 119 to Korean Patent Application No. 10-2019-0037314
filed on Mar. 29, 2019, Korean Patent Application No.
10-2019-0052384 filed on May 3, 2019, and Korean Patent Application
No. 10-2019-0110942 filed on Sep. 6, 2019 in the Korean
Intellectual Property Office, the disclosures of which are
incorporated by reference herein in their entirety.
BACKGROUND
1. Field
[0002] The disclosure relates to a wireless communication system,
and more particularly, to a method and apparatus for repeatedly
transmitting/receiving the same data in a wireless communication
system.
2. Description of Related Art
[0003] To meet increasing demand with respect to wireless data
traffic after the commercialization of 4.sup.th generation (4G)
communication systems, efforts have been made to develop 5.sup.th
generation (5G) or pre-5G communication systems. For this reason,
5G or pre-5G communication systems are called "beyond 4G network"
communication systems or "post long term evolution (post-LTE)"
systems. To achieve high data rates, implementation of 5G
communication systems in an ultra-high frequency millimeter-wave
(mmWave) band (e.g., a 60 GHz band) is being considered. To reduce
path loss and increase a transmission distance in the ultra-high
frequency band for 5G communication systems, various technologies
such as beamforming, massive multiple-input and multiple-output
(massive MIMO), full-dimension MIMO (FD-MIMO), array antennas,
analog beamforming, and large-scale antennas are being studied. To
improve system networks for 5G communication systems, various
technologies such as evolved small cells, advanced small cells,
cloud radio access networks (cloud-RAN), ultra-dense networks,
device-to-device (D2D) communication, wireless backhaul, moving
networks, cooperative communication, coordinated multi-points
(CoMP), and interference cancellation have been developed. In
addition, for 5G communication systems, advanced coding modulation
(ACM) technologies such as hybrid frequency-shift keying (FSK) and
quadrature amplitude modulation (QAM) (FQAM) and sliding window
superposition coding (SWSC), and advanced access technologies such
as filter bank multi-carrier (FBMC), non-orthogonal multiple access
(NOMA), and sparse code multiple access (SCMA), have been
developed.
[0004] The Internet has evolved from a human-based connection
network, where humans create and consume information, to the
Internet of things (IoT), where distributed elements such as
objects exchange information with each other to process the
information. Internet of everything (IoE) technology has emerged,
in which the IoT technology is combined with, for example,
technology for processing big data through connection with a cloud
server. To implement the IoT, various technological elements such
as sensing technology, wired/wireless communication and network
infrastructures, service interface technology, and security
technology are required and, in recent years, technologies related
to sensor networks for connecting objects, machine-to-machine (M2M)
communication, and machine-type communication (MTC) have been
studied. In the IoT environment, intelligent Internet technology
(IT) services may be provided to collect and analyze data obtained
from connected objects to create new value in human life. As
existing information technology (IT) and various industries
converge and combine with each other, the IoT may be applied to
various fields such as smart homes, smart buildings, smart cities,
smart cars or connected cars, smart grids, health care, smart home
appliances, and advanced medical services.
[0005] Various attempts are being made to apply 5G communication
systems to the IoT network. For example, technologies related to
sensor networks, M2M communication, and MTC are being implemented
by using 5G communication technology including beamforming, MIMO,
and array antennas. Application of a cloud RAN as the
above-described big data processing technology may be an example of
convergence of 5G communication technology and IoT technology.
[0006] As described above, with the development of wireless
communication systems, a data transmitting/receiving method for
cooperative communication is required.
SUMMARY
[0007] A method and apparatus for repeatedly transmitting the same
data between a plurality of transmission nodes and a terminal for
network cooperative communication (network coordination) is
provided in a wireless communication system.
[0008] Additional aspects will be set forth in part in the
description which follows and, in part, will be apparent from the
description, or may be learned by practice of the presented
embodiments of the disclosure.
[0009] According to an embodiment of the disclosure, a method by a
user equipment (UE) in a wireless communication system includes:
receiving a first physical downlink shared channel (PDSCH)
transmission and a second PDSCH transmission that carry a same
transport block (TB) and are associated with a first transmission
configuration indicator (TCI) state and a second TCI state,
respectively; determining a transport block size (TBS) of the first
PDSCH transmission; and determining low-density parity-check (LDPC)
base graph corresponding to the transport block based on the
determined TBS for each of the first PDSCH transmission and the
second PDSCH transmission, wherein the determined TBS of the first
PDSCH transmission is applied to the second PDSCH transmission.
[0010] Before undertaking the DETAILED DESCRIPTION below, it may be
advantageous to set forth definitions of certain words and phrases
used throughout this patent document: the terms "include" and
"comprise," as well as derivatives thereof, mean inclusion without
limitation; the term "or," is inclusive, meaning and/or; the
phrases "associated with" and "associated therewith," as well as
derivatives thereof, may mean to include, be included within,
interconnect with, contain, be contained within, connect to or
with, couple to or with, be communicable with, cooperate with,
interleave, juxtapose, be proximate to, be bound to or with, have,
have a property of, or the like; and the term "controller" means
any device, system or part thereof that controls at least one
operation, such a device may be implemented in hardware, firmware
or software, or some combination of at least two of the same. It
should be noted that the functionality associated with any
particular controller may be centralized or distributed, whether
locally or remotely.
[0011] Moreover, various functions described below can be
implemented or supported by one or more computer programs, each of
which is formed from computer readable program code and embodied in
a computer readable medium. The terms "application" and "program"
refer to one or more computer programs, software components, sets
of instructions, procedures, functions, objects, classes,
instances, related data, or a portion thereof adapted for
implementation in a suitable computer readable program code. The
phrase "computer readable program code" includes any type of
computer code, including source code, object code, and executable
code. The phrase "computer readable medium" includes any type of
medium capable of being accessed by a computer, such as read only
memory (ROM), random access memory (RAM), a hard disk drive, a
compact disc (CD), a digital video disc (DVD), or any other type of
memory. A "non-transitory" computer readable medium excludes wired,
wireless, optical, or other communication links that transport
transitory electrical or other signals. A non-transitory computer
readable medium includes media where data can be permanently stored
and media where data can be stored and later overwritten, such as a
rewritable optical disc or an erasable memory device.
[0012] Definitions for certain words and phrases are provided
throughout this patent document, those of ordinary skill in the art
should understand that in many, if not most instances, such
definitions apply to prior, as well as future uses of such defined
words and phrases.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] For a more complete understanding of the present disclosure
and its advantages, reference is now made to the following
description taken in conjunction with the accompanying drawings, in
which like reference numerals represent like parts:
[0014] FIG. 1 illustrates a time-frequency domain transmission
structure of a long term evolution (LTE) or evolved universal
terrestrial radio access (E-UTRA), LTE-advanced (LTE-A), new radio
(NR), or similar wireless communication system;
[0015] FIG. 2 illustrates a frame, subframe, and slot structure in
5.sup.th generation (5G) communication technology;
[0016] FIG. 3 illustrates an example of a bandwidth part (BWP)
configuration according to some embodiments in a wireless
communication system according to an embodiment of the
disclosure;
[0017] FIG. 4 illustrates an example of a BWP indication and change
in a wireless communication system according to an embodiment of
the disclosure;
[0018] FIG. 5 illustrates an example of control region
configuration of a downlink control channel in a wireless
communication system according to an embodiment of the
disclosure;
[0019] FIG. 6 illustrates example of physical downlink shared
channel (PDSCH) frequency-axis resource allocation in a wireless
communication system according to an embodiment of the
disclosure;
[0020] FIG. 7 illustrates an example of PDSCH time-axis resource
allocation in a wireless communication system according to an
embodiment of the disclosure;
[0021] FIG. 8 illustrates an example of PDSCH time-axis resource
allocation according to subcarrier spacing of a data channel and a
control channel in a wireless communication system according to an
embodiment of the disclosure;
[0022] FIG. 9 illustrates a method of determining a low-density
parity-check (LDPC) base graph used for encoding of a transport
block (TB) and decoding of a codeword in a wireless communication
system according to an embodiment of the disclosure;
[0023] FIG. 10 illustrates an example of slot-by-slot repeated
transmission (slot aggregation) in a wireless communication system
according to an embodiment of the disclosure;
[0024] FIG. 11 illustrates an example of antenna port configuration
and resource allocation for cooperative communication in a wireless
communication system according to an embodiment of the
disclosure;
[0025] FIG. 12 illustrates an example of a downlink control
information (DCI) configuration for cooperative communication in a
wireless communication system according to an embodiment of the
disclosure;
[0026] FIG. 13A illustrates an example of repeated transmission of
multiple transmission and reception points (TRPs) based on various
resource allocation methods in a wireless communication system
according to an embodiment of the disclosure;
[0027] FIG. 13B illustrates an example of repeated transmission of
multiple TRPs based on various resource allocation methods in a
wireless communication system according to an embodiment of the
disclosure;
[0028] FIG. 13C illustrates an example of repeated transmission of
multiple TRPs based on various resource allocation methods in a
wireless communication system according to an embodiment of the
disclosure;
[0029] FIG. 13D illustrates an example of repeated transmission of
multiple TRPs based on various resource allocation methods in a
wireless communication system according to an embodiment of the
disclosure;
[0030] FIG. 14 illustrates an example of redefinition of a DCI
payload in repeated transmission of multiple TRPs in a wireless
communication system according to an embodiment of the
disclosure;
[0031] FIG. 15 illustrates a structure of a terminal in a wireless
communication system according to an embodiment of the disclosure;
and
[0032] FIG. 16 illustrates a structure of a base station in a
wireless communication system according to an embodiment of the
disclosure.
DETAILED DESCRIPTION
[0033] FIGS. 1 through 16, discussed below, and the various
embodiments used to describe the principles of the present
disclosure in this patent document are by way of illustration only
and should not be construed in any way to limit the scope of the
disclosure. Those skilled in the art will understand that the
principles of the present disclosure may be implemented in any
suitably arranged system or device.
[0034] Hereinafter, embodiments of the disclosure will be described
in detail with reference to the accompanying drawings.
[0035] In describing the embodiments of the disclosure,
descriptions of technical contents that are well known in the
technical field to which the disclosure belongs and are not
directly related to the disclosure will be omitted. This is to more
clearly convey the subject matter of the disclosure without
obscuration thereof by omitting unnecessary descriptions
thereof.
[0036] For the same reason, some components in the accompanying
drawings may be exaggerated, omitted, or schematically illustrated.
Also, the size of each component may not completely reflect the
actual size thereof. In the drawings, the same or corresponding
elements may be given the same reference numerals.
[0037] Advantages and features of the disclosure and methods of
achieving the same will be apparent from the embodiments of the
disclosure described below in detail with reference to the
accompanying drawings. The disclosure may, however, be embodied in
many different forms and should not be construed as being limited
to the embodiments of the disclosure described below; rather, these
embodiments are provided to complete the disclosure and fully
convey the scope of the disclosure to those of ordinary skill in
the art and the disclosure will be defined only by the scope of the
claims. Like reference numerals refer to like elements throughout
the specification.
[0038] Throughout the disclosure, the expression "at least one of
a, b or c" indicates only a, only b, only c, both a and b, both a
and c, both b and c, all of a, b, and c, or variations thereof.
[0039] Examples of a terminal may include a user equipment (UE), a
mobile station (MS), a cellular phone, a smartphone, a computer, a
multimedia system capable of performing a communication function,
or the like.
[0040] In the disclosure, a controller may also be referred to as a
processor.
[0041] Throughout the specification, a layer (or a layer apparatus)
may also be referred to as an entity.
[0042] It will be understood that each block of process flowchart
diagrams and combinations of flowchart diagrams may be performed by
computer program instructions. Because these computer program
instructions may be mounted on a processor of a general-purpose
computer, special-purpose computer, or other programmable data
processing equipment, the instructions executed through a processor
of a computer or other programmable data processing equipment may
generate a means of performing the functions described in the
flowchart block(s). Because these computer program instructions may
be stored in a computer-usable or computer-readable memory that may
be directed to a computer or other programmable data processing
equipment to implement a function in a particular manner, the
instructions stored in the computer-usable or computer-readable
memory may also produce a production item containing an instruction
means of performing the functions described in the flowchart
block(s). Because the computer program instructions may also be
mounted on a computer or other programmable data processing
equipment, the instructions performing a series of operations on
the computer or other programmable data processing equipment to
generate a computer-implemented process to perform the computer or
other programmable data processing equipment may also provide
operations for executing the functions described in the flowchart
block(s).
[0043] Also, each block may represent a portion of a module,
segment, or code including one or more executable instructions for
executing one or more specified logical functions. Also, it should
be noted that the functions mentioned in the blocks may also occur
in a different order in some alternative implementation examples.
For example, two blocks illustrated in succession may actually be
performed substantially at the same time or may sometimes be
performed in the opposite order depending on the corresponding
function.
[0044] In this case, the term ".about.unit" used in the present
embodiment of the disclosure may refer to a software component or a
hardware component such as a field programmable gate array (FPGA)
or an application specific integrated circuit (ASIC) and the
".about.unit" may perform certain functions. However, the
".about.unit" is not limited to software or hardware. The
".about.unit" may be configured to be in an addressable storage
medium or may be configured to operate one or more processors.
Thus, according to an embodiment of the disclosure, the
".about.unit" may include components such as software components,
object-oriented software components, class components, and task
components and may include processes, functions, attributes,
procedures, subroutines, segments of program code, drivers,
firmware, microcode, circuits, data, databases, data structures,
tables, arrays, and variables. A function provided by the
components and ".about.units" may be associated with the smaller
number of components and ".about.units" or may be further divided
into additional components and ".about.units." In addition, the
components and ".about.units" may be implemented to operate one or
more central processing units (CPUs) in a device or a security
multimedia card. Also, according to an embodiment of the
disclosure, the ".about.unit" may include one or more
processors.
[0045] Hereinafter, operation principles of the disclosure will be
described in detail with reference to the accompanying drawings. In
the following description of the disclosure, detailed descriptions
of well-known functions or configurations will be omitted because
they would unnecessarily obscure the subject matters of the
disclosure. Also, terms to be described below may be terms defined
considering functions in the disclosure and may vary according to
users' or operators' intentions or practices. Therefore, the
definition thereof should be made based on the contents throughout
the specification. Hereinafter, a base station may be an agent
performing terminal resource allocation and may be at least one of
a gNode B, an eNode B, a Node B, a base station (BS), a radio
access unit, a base station controller, or a node on a network.
Examples of a terminal may include a user equipment (UE), a mobile
station (MS), a cellular phone, a smartphone, a computer, or a
multimedia system capable of performing a communication function.
However, the disclosure is not limited thereto.
[0046] Hereinafter, the disclosure provides technology for a
terminal to receive broadcast information from a base station in a
wireless communication system. The disclosure relates to a
communication method and system for convergence of 5.sup.th
generation (5G) communication systems and Internet of things (IoT)
technology to support higher data rates after 4.sup.th generation
(4G) communication systems. The disclosure is applicable to
intelligent services (e.g., smart home, smart building, smart city,
smart car or connected car, health care, digital education, retail,
security, and safety services) based on 5G communication technology
and IoT technology.
[0047] In the following description, terms referring to broadcast
information, terms referring to control information, terms related
to communication coverage, terms referring to state changes (e.g.,
events), terms referring to network entities, terms referring to
messages, terms referring to components of an apparatus, and the
like are illustrated for convenience of description. Thus, the
disclosure is not limited to the terms described below and other
terms having equivalent technical meanings may be used.
[0048] In the following description, terms and names defined in the
3.sup.rd generation partnership project long term evolution (3GPP
LTE) standards may be used for convenience of description. However,
the disclosure is not limited to those terms and names and is
equally applicable to systems according to other standards.
[0049] Wireless communication systems providing voice-based
services are being developed to broadband wireless communication
systems providing high-speed and high-quality packet data services
according to communication standards such as high speed packet
access (HSPA), long term evolution (LTE) or evolved universal
terrestrial radio access (E-UTRA), LTE-advanced (LTE-A), LTE-Pro of
3GPP, high rate packet data (HRPD) and ultra mobile broadband (UMB)
of 3GPP2, and 802.16e of the Institute of Electrical and
Electronics Engineers (IEEE).
[0050] As a representative example of the broadband wireless
communication systems, LTE systems employ orthogonal frequency
division multiplexing (OFDM) for a downlink and employs single
carrier-frequency division multiple access (SC-FDMA) for an uplink.
The uplink refers to a radio link for transmitting data or a
control signal from a terminal (e.g., a user equipment (UE) or a
mobile station (MS)) to a base station (e.g., an evolved Node B
(eNB) or a base station (BS)), and the downlink refers to a radio
link for transmitting data or a control signal from the base
station to the terminal. The above-described multiple access
schemes distinguish between data or control information of
different users by allocating time-frequency resources for the data
or control information of the users not to overlap each other, that
is, to achieve orthogonality therebetween.
[0051] As post-LTE systems, 5G systems need to support services
capable of reflecting and satisfying various requirements of users,
service providers, and the like. Services considered for the 5G
systems include enhanced mobile broadband (eMBB), massive
machine-type communication (mMTC), and ultra-reliability
low-latency communication (URLLC) services.
[0052] According to an embodiment of the disclosure, the eMBB aims
to provide an improved data rate than the data rate supported by
the existing LTE, LTE-A, or LTE-Pro. For example, in a 5G
communication system, the eMBB may be able to provide a peak data
rate of 20 Gbps in a downlink and a peak data rate of 10 Gbps in an
uplink from the viewpoint of a base station. Simultaneously, it is
necessary to provide an increased user-perceived data rate of a
terminal. In order to satisfy such requirements, there is a need
for an improvement in transmission/reception technology including
an improved multiple-input multiple-output (MIMO) transmission
technology. Also, the data rate required in the 5G communication
system may be satisfied by using a frequency bandwidth wider than
20 MHz in the 3 GHz to 6 GHz or 6 GHz or more frequency band,
instead of the 2 GHz band used by the current LTE.
[0053] Simultaneously, the mMTC is being considered to support
application services such as Internet of Thing (IoT) in 5G
communication systems. In order to efficiently provide the IoT, the
mMTC may require the support for access of a large terminal in a
cell, improved terminal coverage, improved battery time, reduced
terminal cost, and the like. Because the IoT is attached to various
sensors and various devices to provide a communication function, it
may be able to support a large number of terminals (e.g., 1,000,000
terminals/km.sup.2) in a cell. Also, because a terminal supporting
the mMTC is likely to be located in a shadow region failing to be
covered by the cell, such as the basement of a building, due to the
characteristics of the service, it may require wider coverage than
other services provided by the 5G communication systems. The
terminal supporting the mMTC may be configured as a low-cost
terminal and may require a very long battery life time because it
is difficult to frequently replace the battery of the terminal.
[0054] Lastly, the URLLC may provide communications providing
ultra-low latency and ultra reliability, as services for remote
control of robots or machinery, industrial automation, unmanned
aerial vehicles, remote health care, emergency alerts, and the
like, as cellular-based wireless communication services used for
mission-critical purposes. For example, a service supporting the
URLLC may satisfy an air interface latency of less than 0.5
milliseconds and simultaneously has a requirement for a packet
error rate of 10.sup.-5 or less. Thus, for the service supporting
the URLLC, the 5G system may provide a smaller transmit time
interval (TTI) than other services and simultaneously has a design
requirement for allocating wide resources in a frequency band.
However, the above-described mMTC, URLLC, and eMBB are merely
examples of different service types, and the service types to which
the disclosure is applied are not limited thereto.
[0055] The above-described services considered in the 5G
communication systems may be provided in a converged manner with
each other based on one framework. That is, for efficient resource
management and control, respective services may be integrated,
controlled, and transmitted as one system rather than operated
independently.
[0056] Also, although embodiments of the disclosure will be
described below by using an LTE, LTE-A, LTE Pro, or NR system as an
example, the embodiments of the disclosure may also be applied to
other communication systems having similar technical backgrounds or
channel forms. Also, the embodiments of the disclosure may also be
applied to other communication systems through some modifications
without departing from the scope of the disclosure by the judgment
of those of ordinary skill in the art.
[0057] The disclosure relates to a method and apparatus for
repeatedly transmitting data and control signals between a terminal
and a plurality of transmission nodes performing cooperative
communication to improve communication reliability.
[0058] According to the disclosure, when network cooperative
communication is used in a wireless communication system, the
reliability of terminal reception data/control signals may be
improved.
[0059] Hereinafter, a frame structure of the 5G system will be
described in more detail with reference to the accompanying
drawings. FIG. 1 is a diagram illustrating a time-frequency domain
transmission structure of an LTE, LTE-A, NR, or similar wireless
communication system.
[0060] FIG. 1 illustrates a basic structure of a time-frequency
region that is a radio resource region in which data or a control
channel is transmitted in the 5G system.
[0061] Referring to FIG. 1, the horizontal axis in FIG. 1
represents a time domain and the vertical axis represents a
frequency domain. The basic unit of resources in the time and
frequency domain may be a resource element (RE) 1-01 and may be
defined by one orthogonal frequency division multiplexing (OFDM)
symbol (RE) 1-02 on the time axis and one subcarrier 1-03 on the
frequency axis. In the frequency domain, N.sub.sc.sup.RB (e.g., 12)
consecutive REs may constitute one resource block (RB) 1-04.
[0062] FIG. 2 illustrates a frame, subframe, and slot structure in
the 5G.
[0063] Referring to FIG. 2, FIG. 2 illustrates an example of a
structure of frame (RE) 2-00, subframe 2-01, and slot 2-02. One
frame 2-00 may be defined as 10 ms. One subframe 2-01 may be
defined as 1 ms, and thus, one frame 2-00 may include a total of 10
subframes 2-01. One slot 2-02 or 2-03 may be defined as 14 OFDM
symbols (i.e., the number of symbols per slot
(N.sub.symb.sup.slot)=14). One subframe 2-01 may include one or
more slots 2-02 or 2-03, and the number of slots 2-02 or 2-03 per
subframe 2-01 may vary according to configuration values .mu.(2-04
and 2-05) for subcarrier spacing. In the example of FIG. 2, a case
where subcarrier spacing values are set to .mu.=0 (2-04) and .mu.=1
(2-05) is illustrated. In the case of .mu.=0 (2-04), one subframe
2-01 may include one slot 2-02, and in the case of .mu.=1 (2-05),
one subframe 2-01 may include two slots 2-03. That is, the number
of slots per subframe (N.sub.slot.sup.subframe.mu.) may vary
according to the configuration values .mu. for the subcarrier
spacing, and accordingly, the number of slots per frame
(N.sub.slot.sup.frame.mu.) may vary. N.sub.slot.sup.subframe.mu.and
N.sub.slot.sup.frame.mu.according to the subcarrier spacing values
.mu. may be defined as in Table 1 below.
TABLE-US-00001 TABLE 1 Subcarrier spacing values .mu.
N.sup.slot.sub.symb N.sup.frame, .mu..sub.slot N.sup.subframe,
.mu..sub.slot 0 14 10 1 1 14 20 2 2 14 40 4 3 14 80 8 4 14 160 16 5
14 320 32
[0064] In the NR, one component carrier CC or serving cell may
include up to 250 or more RBs. Thus, when a terminal always
receives the entire serving cell bandwidth as in LTE, the power
consumption of the terminal may be extreme, and in order to solve
this limitation, a base station may configure one or more bandwidth
parts (BWPs) to the terminal to support the terminal to change a
reception region in the cell. In the NR, the base station may
configure "initial BWP," which is a bandwidth of CORESET #0 (or
common search space (CSS)), to the terminal through MIB.
Thereafter, the base station may configure an initial BWP (first
BWP) of the terminal through radio resource control (RRC) signaling
and notify at least one piece of BWP configuration information that
may be indicated through downlink control information (DCI) in the
future. Thereafter, the base station may notify a BWP ID through
the DCI to indicate which band maybe used by the terminal. When the
terminal fails to receive the DCI in the currently allocated BWP
for a certain time or more, the terminal may return to "default
BWP" and attempt to receive the DCI.
[0065] FIG. 3 illustrates an example of a BWP configuration in a
wireless communication system according to an embodiment of the
disclosure.
[0066] Referring to FIG. 3, FIG. 3 illustrates an example in which
a terminal (UE) bandwidth 3-00 is configured as two bandwidth
parts, that is, a bandwidth part #1 3-05 and a bandwidth part #2
3-10. The base station may configure one or more bandwidth parts to
the terminal and may configure information as in Table 2 below for
each bandwidth part.
TABLE-US-00002 TABLE 2 Configuration information BWP ::= SEQUENCE {
bwp-Id BWP-Id, locationAndBandwidth INTEGER (1..65536),
subcarrierSpacing ENUMERATED {n0, n1, n2, n3, n4, n5}, cyclicPrefix
enumerated { extended } }
[0067] In addition to the configuration information described in
Table 2, various parameters related to the bandwidth part may be
configured to the terminal. The above information may be
transmitted from the base station to the terminal through higher
layer signaling, for example, RRC signaling. At least one bandwidth
part among the configured one or more bandwidth parts may be
activated. Information about the activation/deactivation of the
configured bandwidth part may be semi-statically transmitted from
the base station to the terminal through RRC signaling or may be
dynamically transmitted through a medium access control (MAC)
control element (CE) or DCI.
[0068] The configuration for the bandwidth part supported by the 5G
communication system may be used for various purposes.
[0069] For example, when the bandwidth supported by the terminal is
smaller than the system bandwidth, only the bandwidth supported by
the terminal may be configured through the setting for the
bandwidth part. For example, the frequency position of the
bandwidth part may be configured to the terminal in Table 2, and
thus, the terminal may transmit/receive data at a particular
frequency position in the system bandwidth.
[0070] As another example, for the purpose of supporting different
numerologies, the base station may configure a plurality of
bandwidth parts to the terminal. For example, in order to support
data transmission/reception using a subcarrier spacing of 15 kHz
and a subcarrier spacing of 30 kHz to a random terminal, two
bandwidth parts may be configured to use subcarrier spacings of 15
kHz and 30 kHz, respectively. Different bandwidth parts may be
frequency-division-multiplexed (FDMed), and when data is to be
transmitted/received at particular subcarrier spacings, the
bandwidth part configured at the particular subcarrier spacings may
be activated.
[0071] As another example, for the purpose of reducing power
consumption of the terminal, the base station may configure
bandwidth parts having bandwidths of different sizes to the
terminal. For example, when the terminal supports a very large
bandwidth, for example, a bandwidth of 100 MHz, and always
transmits/receives data with the bandwidth, it may cause very large
power consumption. Particularly, it may be very inefficient in
terms of power consumption for the terminal to monitor an
unnecessary downlink control channel for a large bandwidth of 100
MHz while there is no traffic. Therefore, in order to reduce power
consumption of the terminal, the base station may configure a
bandwidth part of a relatively small bandwidth, for example, a
bandwidth part of 20 MHz, to the terminal. The terminal may perform
a monitoring operation in a 20 MHz bandwidth part in a situation
where there is no traffic and may transmit/receive data by using a
100 MHz bandwidth part according to the indication of the base
station when data is generated.
[0072] FIG. 4 illustrates an example of a BWP indication and change
in a wireless communication system according to an embodiment of
the disclosure.
[0073] Referring to FIG. 4, as described in Table 2, the base
station may configure one or more bandwidth parts to the terminal
and may notify the terminal of information about the bandwidth of a
bandwidth part, the frequency position of a bandwidth part, the
numerology of a bandwidth part, or the like by the configuration
for each bandwidth part. FIG. 4 illustrates an example in which two
bandwidth parts, that is, a bandwidth part #1 (BWP #1) 4-05 and a
bandwidth part #2 (BWP #2) 4-10, are configured in a terminal
bandwidth 4-00 to one terminal. One or more bandwidth parts in the
configured bandwidth may be activated, and an example in which one
bandwidth part is activated may be considered in FIG. 4. In FIG. 4,
the bandwidth part #1 4-05 among the bandwidth parts configured in
a slot #0 4-25 is activated, and the terminal may monitor a
physical downlink control channel (PDCCH) in a control region #1
4-45 set in the bandwidth part #1 4-05 and may transmit/receive
data 4-55 in the bandwidth part #1 4-05. The control region in
which the terminal receives the PDCCH may vary according to which
bandwidth part among the configured bandwidth parts is activated,
and accordingly, the bandwidth in which the terminal monitors the
PDCCH may vary.
[0074] The base station may further transmit, to the terminal, an
indicator for changing the configuration for the bandwidth part.
Here, changing the configuration for the bandwidth part may be
considered the same as an operation of activating a particular
bandwidth part (e.g., changing the activation from a bandwidth part
A to a bandwidth part B). The base station may transmit a
configuration change indicator (configuration switching indicator)
to the terminal in a particular slot, and the terminal may
determine a bandwidth part to be activated by applying the changed
configuration according to the configuration change indicator from
a particular time point after receiving the configuration change
indicator from the base station and may monitor the PDCCH in the
control region configured in the activated bandwidth part.
[0075] In FIG. 4, the base station may transmit a configuration
switching indicator 4-15 indicating the change of the activated
bandwidth part from the existing bandwidth part #1 4-05 to the
bandwidth part #2 4-10, to the terminal in a slot #1 4-30. After
receiving the indicator, the terminal may activate the bandwidth
part #2 4-10 according to the content of the indicator. In this
case, a transition time 4-20 for changing the bandwidth part may be
required, and accordingly, a time point for changing and applying
the bandwidth part to be activated may be determined. FIG. 4
illustrates a case where a transition time 4-20 of one slot is
required after receiving the configuration switching indicator
4-15. Data transmission/reception may not be performed in the
transition time 4-20 (4-60). Accordingly, the bandwidth part #2
4-10 may be activated in a slot #2 4-35 to perform an operation of
transmitting/receiving a control channel and data in the
corresponding bandwidth part.
[0076] The base station may pre-configure one or more bandwidth
parts to the terminal by higher layer signaling (e.g., RRC
signaling), and the configuration switching indicator 4-15 may
indicate activation by mapping with one of the bandwidth part
configurations preset by the base station. For example, an
indicator of log.sub.2N bits may select and indicate one of N
pre-configured bandwidth parts. In Table 3 below, an example of
indicating configuration information about a bandwidth part by
using a 2-bit indicator is described.
TABLE-US-00003 TABLE 3 Indication of configuration information
Indicator Bandwidth part settings 00 Bandwidth setting A set by
higher layer signaling 01 Bandwidth setting B set by higher layer
signaling 10 Bandwidth setting C set by higher layer signaling 11
Bandwidth setting D set by higher layer signaling
[0077] The configuration switching indicator 4-15 for the bandwidth
part described in FIG. 4 may be transmitted from the base station
to the terminal in the form of medium access control (MAC) control
element (CE) signaling or L1 signaling (e.g., common DCI,
group-common DCI, or terminal-specific DCI).
[0078] According to the configuration switching indicator 4-15 for
the bandwidth part described in FIG. 4, from which time point the
bandwidth part activation maybe applied may depend on the
following. From which time point the configuration switching maybe
applied may depend on a predefined value (e.g., applied after N
(=1) slot after receiving the configuration switching indicator),
may be configured by the base station to the terminal through
higher layer signaling (e.g., RRC signaling), or may be partially
included and transmitted in the content of the configuration
switching indicator 4-15. Alternatively, it may be determined by a
combination of the above methods. After receiving the configuration
switching indicator 4-15 for the bandwidth part, the terminal may
apply the changed configuration from the time point obtained by the
above method.
[0079] Hereinafter, a downlink control channel in the 5G
communication system will be described in more detail with
reference to the drawings.
[0080] FIG. 5 illustrates an example of control region
configuration of a downlink control channel in a wireless
communication system according to an embodiment of the
disclosure.
[0081] Referring to FIG. 5, FIG. 5 illustrates an example in which
two control regions (control region #1 5-01 and control region #2
5-02) are configured in a bandwidth part 5-10 of the terminal on
the frequency axis and one slot 5-20 on the time axis. The control
regions 5-01 and 5-02 may be configured to particular frequency
resources 5-03 in the entire terminal bandwidth part 5-10 on the
frequency axis. The control regions 5-01 and 5-02 may be configured
by one or more OFDM symbols on the time axis and may be defined by
a control region length 5-04. In the example of FIG. 5, the control
region #1 5-01 may be configured by a control region length of two
symbols, and the control region #2 5-02 may be configured by a
control region length of one symbol.
[0082] The control region in the 5G described above may be
configured by the base station to the terminal through higher layer
signaling (e.g., system information, master information block
(MIB), or radio resource control (RRC) signaling). Configuring the
control region in the terminal may mean providing the terminal with
information such as a control region identifier, a frequency
position of the control region, or a symbol length of the control
region. For example, information of Table 4 may be included
therein.
TABLE-US-00004 TABLE 4 Configuration information ControlResourceSet
::= SEQUENCE { -- Corresponds to L1 parameter ' `CORESET-ID`
ControlResourceSetId ControlResourceSetId, (control region
identifier) frequencyDomainResources BIT STRING (SIZE (45)),
(frequency domain resource allocation information) duration INTEGER
(1..maxCoReSetDuration), (time domain resource allocation
information) cce-REG-MappingType CHOICE { (CCE-to-REG mapping
method) interleaved SEQUENCE { reg-BundleSize ENUMERATED {n2, n3,
n6}, (REG bundle size) precoderGranularity ENUMERATED
{sameAsREG-bundle, allContiguousRBs), interleaverSize ENUMERATED
{n2, n3, n6J (interleaver size) shiftindex
INTEGER(0..maxNrofPhysicalResourceBlocks-1) OPTIONAL (interleaver
shift) }, nonInterleaved NULL }, tci-StatesPDCCH SEQUENCE(SIZE
(1..maxNrofTCI- StatesPDCCH)) OF TCI-StateId OPTIONAL, (QCL
configuration information) tci-PresentInDCI ENUMERATED {enabled}
}
[0083] In Table 4, tci-StatesPDCCH (simply referred to as TCI
state) configuration information may include information of a
channel state information reference signal (CSI-RS) index or one or
more synchronization signal(SS)/physical broadcast channel (PBCH)
block indexes having a quasi co-located (QCL) relationship with a
demodulation reference signal (DMRS) transmitted in the
corresponding control region.
[0084] Next, DCI in the NR will be described in detail. In the NR,
scheduling information about uplink data (or physical uplink shared
channel (PUSCH)) or downlink data (or physical downlink shared
channel (PDSCH)) may be transmitted from the base station to the
terminal through the DCI. For efficient control channel reception
of the terminal, various types of DCI formats may be provided as in
Table 5 below according to purposes.
TABLE-US-00005 TABLE 5 Type of DCI format DCI format Usage 0_0
Scheduling of PUSCH in one cell 0_1 Scheduling of PUSCH in one cell
1_0 Scheduling of PDSCH in one cell 1_1 Scheduling of PDSCH in one
cell 2_0 Notifying a group of UEs of the slot format 2_1 Notifying
a group of UEs of the PRB(s) and OFDM symbol(s) where UE may assume
no transmission is intended for the UE 2_2 Transmission of TPC
commands for PUCCH and PUSCH 2_3 Transmission of a group of TPC
commands for SRS transmissions by one or more UEs
[0085] The terminal may monitor a fallback DCI format and a
non-fallback DCI format with respect to the PUSCH or PDSCH. The
fallback DCI format may include a fixed field predefined between
the base station and the terminal, and the non-fallback DCI format
may include a configurable field.
[0086] The DCI may be transmitted through a physical downlink
control channel (PDCCH) through a channel coding and modulation
process. A cyclic redundancy check (CRC) may be attached to a DCI
message payload, and the CRC may be scrambled with a radio network
temporary identifier (RNTI) corresponding to the identity of the
terminal. Different RNTIs may be used according to the purpose of a
DCI message, for example, terminal-specific (UE-specific) data
transmission, a power control command, or a random access response.
That is, the RNTI may not be explicitly transmitted but may be
included and transmitted in a CRC calculation process. Upon
receiving the DCI message transmitted on the PDCCH, the terminal
may check the CRC by using the allocated RNTI, and, when the CRC
check result is correct, the terminal may know that the message is
transmitted to the terminal.
[0087] For example, the DCI for scheduling the PDSCH about system
information (SI) may be scrambled with an SI-RNTI. The DCI for
scheduling the PDSCH about a random access response (RAR) message
may be scrambled with an RA-RNTI. The DCI for scheduling the PDSCH
about a paging message may be scrambled with a P-RNTI. The DCI for
notifying a slot format indicator (SFI) may be scrambled with an
SFI-RNTI. The DCI for notifying a transmit power control (TPC) may
be scrambled with a TPC-RNTI. The DCI for scheduling a
terminal-specific PDSCH or PUSCH may be scrambled with a C-RNTI
(cell RNTI).
[0088] A DCI format 0_0 may be used as fallback DCI for scheduling
the PUSCH, and in this case, the CRC may be scrambled with a
C-RNTI. The DCI format 0_0 in which the CRC is scrambled with the
C-RNTI may include, for example, information of Table 6 below.
TABLE-US-00006 TABLE 6 Information configuration Identifier for DCI
formats - [1] bit Frequency domain resource assignment -[.left
brkt-top.log.sub.2(N.sup.UL, BWP.sub.RB(N.sup.UL, BWP.sub.RB +
1)/2).right brkt-bot.] bits Time domain resource assignment - X
bits Frequency hopping flag- 1 bit. Modulation and coding scheme- 5
bits New data indicator- 1 bit Redundancy version - 2 bits HARQ
process number- 4 bits IPG command for scheduled PUSCH - [2] bits
UL/SUL indicator - 0 or 1 bit
[0089] A DCI format 0_1 may be used as non-fallback DCI for
scheduling the PUSCH, and in this case, the CRC may be scrambled
with a C-RNTI. The DCI format 0_1 in which the CRC is scrambled
with the C-RNTI may include, for example, information of Table 7
below.
TABLE-US-00007 TABLE 7 Information configuration Carrier indicator
- 0 or 3 bits UL/SUL indicator - 0 or 1 bit Identifier for DCI
formats - [1] bits Bandwidth part indicator - 0, 1 or 2 bit
Frequency domain resource assignment For resource allocation type
0, .left brkt-top.N.sub.RB.sup.UL,BWP/P.right brkt-bot. bits For
resource allocation type 1, .left
brkt-top.log.sub.2(N.sub.RB.sup.UL,BWP(N.sub.RB.sup.UL,BWP +
1)/2).right brkt-bot. bits Time domain resource assignment - 1, 2,
3, or 4 bits VRB-to-FRB mapping - 0 or 1 bit, only for resource
allocation type 1. 0 bit if only resource allocation type 0 is
configured; 1 bit otherwise. Frequency hopping flag - 0 of 1 bit,
only for resource at type 1. 0 bit if only resource allocation type
0 is configured; 1 bit otherwise. Modulation and coding scheme - 5
bits New data indicator - 1 bit Redundancy version - 2 bits HARQ
process number - 4 bits 1st downlink assionment index - 1 or 2 bits
1 bit for semi-static HARQ-ACK codebook; 2 bits for dynamic
HARQ-ACK codebook with single HARQ-ACK codebook. 2nd downlink
assignment index-0 or 2 bits 2 bits for dynamic HARQ-ACK codebook
with two HARQ-ACK sub-codebooks; 0 bit otherwise. TPC command for
scheduled PUSCH - 2 bits SRS resource indicator - log 2 ( k = 1 L ?
( N SRS k ) ) or log 2 ( N SRS ) bits ##EQU00001## log 2 ( k = 1 L
? ( N SRS k ) ) bits for non - codebook based ##EQU00002## PUSCH
transmission; .left brkt-top.log.sub.2(N.sub.SRS).right brkt-bot.
bits for codebook based PUSCH transmission. Precoding information
and number of layers - up to 6 bits Antenna ports - up to 5 bit SRS
request - 2 bits CSI request - 0, 1, 2, 3, 4, 5, or 6 bits CBG
transmission information - 0, 2, 4, 6, or 8 bits PTRS-DMRS
association - 0 or 2 bits. beta_offset indicator - 0 or 2 bits DMRS
sequence initialization - 0 or 1 bit ? indicates text missing or
illegible when filed ##EQU00003##
[0090] A DCI format 1_0 may be used as fallback DCI for scheduling
the PDSCH, and in this case, the CRC may be scrambled with a
C-RNTI. The DCI format 1_0 in which the CRC is scrambled with the
C-RNTI may include, for example, information of Table 8 below.
TABLE-US-00008 TABLE 8 Information configuration Identifier for DCI
formats- 1] bit Frequency domain resource assignment-[.left
brkt-top.log.sub.3(N.sup.DL, BWP.sub.RB(N.sup.DL, BWP.sub.RB +
1)/2).right brkt-bot.] bits Time domain resource assigsment-X bits
VRB-to-PRB mapping- 1 bit. Modulation and coding scheme-5 bits New
data indicator-1 bit Redundancy version-2 bits HARQ process
number-4 bits Dowlink assignment index-2 bits TPC command for
scheduled PUCCH-[2] bits PUCCH resource indicator-3 bits
PDSCH-to-HARQ feedback timing indicator-[3] bits
[0091] A DCI format 1_1 may be used as non-fallback DCI for
scheduling the PDSCH, and in this case, the CRC may be scrambled
with a C-RNTI. The DCI format 1_1 in which the CRC is scrambled
with the C-RNTI may include, for example, information of Table 9
below.
TABLE-US-00009 TABLE 9 Information configuration Carrier
indicator-0 or 3 bits identifier for DCI formats-[1] bits Bandwidth
part indicator-0, 1 or 2 bits Frequency domain resource assignment
For resource allocation type 0, .left brkt-top.N.sup.DL,
BWP.sub.RB/P.right brkt-bot. bits For resource allocation type 1,
.left brkt-top.log.sub.3(N.sup.DL, BWP.sub.RB(N.sup.DL, BWP.sub.RB
+ 1)/2.right brkt-bot. bits Time domain resource assignment-1, 2,
3, or 4 bits VRB-to-PRB mapping-0 or 1 bit, only for resource
allocation type 1. 0 bit if only resource allocation type 0 is
configured: 1 bit otherwise. PRB bundling size indicator-0 or 1 bit
Rate matching indicator-0, 1, or 2 bits ZP CSI-RS trigger-0, 1, or
2 bits For transport block 2: Modulation and coding scfeeme-5 bits
New data indicator-1 bit Redundancy version-2 bits For transport
block 2: Modulation: and coding scheme-5 bits New data indicator-1
bit Redundancy version-2 bits HARQ process number-4 bils Downlink
assignment index-0 or 2 or 4 bit TPC command for scheduled PUCCH-2
bits PUCCH resource indicator-3 bits PDSCH-to-HARQ_feedback timing
indicator-3 bits Antenna ports-4, 5 or 6 bits Transmission
configuration indication-0 or 3 bits SRS request-2 bits CBG
transmission information-0, 2, 4, 6, or 8 bits CBG flushing out
information-0 or 1 bit DMRS sequence initialization-1 bit
[0092] In the NR, in addition to the frequency-axis resource
candidate allocation through the
[0093] BWP indication, the following detailed frequency-domain
resource allocation methods (FD-RAs) may be provided through the
DCI.
[0094] FIG. 6 illustrates an example of PDSCH frequency-axis
resource allocation in a wireless communication system according to
an embodiment of the disclosure.
[0095] Referring to FIG. 6, when a terminal is configured to use
only a resource type 0 through higher layer signaling (6-00), some
DCI for allocating a PDSCH to the terminal may have a bitmap
including NRBG bits. The conditions for this will be described
again below. In this case, NRBG refers to the number of resource
block groups (RBGs) determined as in Table 10 according to an
higher layer parameter rbg-Size and a BWP size allocated by a BWP
indicator, and data may be transmitted in the RBG represented as
"1" by the bitmap.
TABLE-US-00010 TABLE 10 A number of RBGs Bandwidth Part Size
Configuration 1 Configuration 2 1-36 2 4 37-72 4 8 73-144 8 16
145-275 16 16
[0096] When a terminal is configured to use only a resource type 1
through higher layer signaling (6-05), some DCI for allocating a
PDSCH to the terminal may have frequency-axis resource allocation
information including .left
brkt-top.log.sub.2(N.sub.RB.sup.DL,BWP(N.sub.RB.sup.DL,BWP+1)/2).right
brkt-bot. bits. The base station may configure a starting VRB 6-20
and a length 6-25 of a frequency-axis resource consecutively
allocated therefrom.
[0097] When a terminal is configured to use both the resource type
0 and the resource type 1 through higher layer signaling (6-10),
some DCI for allocating a PDSCH to the terminal may have
frequency-axis resource allocation information including bits of a
large value 6-35 among a payload 6-15 for setting the resource type
0 and payloads 6-20 and 6-25 for configuring the resource type 1.
The conditions for this will be described again below. In this
case, one bit may be added to the foremost part (MSB) of the
frequency-axis resource allocation information in the DCI, and when
the bit is "0," the resource type 0 may be indicated to be used,
and when the bit is "1," the resource type 1 may be indicated to be
used.
[0098] FIG. 7 illustrates an example of PDSCH time-axis resource
allocation in a wireless communication system according to an
embodiment of the disclosure.
[0099] Referring to FIG. 7, the base station may indicate the
time-axis position of a PDSCH resource according to subcarrier
spacings .mu..sub.PDSCH and .mu..sub.PDCCH of a data channel and a
control channel configured through an higher layer, a scheduling
offset K.sub.0 value, an OFDM symbol start position 7-00 and a
length 7-05 in one slot dynamically indicated through the DCI.
[0100] FIG. 8 illustrates an example of PDSCH time-axis resource
allocation according to subcarrier spacing of a data channel and a
control channel in a wireless communication system according to an
embodiment of the disclosure.
[0101] Referring to FIG. 8, when the subcarrier spacings of the
data channel and the control channel are equal to each other (8-00,
.mu..sub.PDSCH=.mu..sub.PDCCH), because the slot numbers for data
and control are equal to each other, the base station and the
terminal may know that a scheduling offset occurs according to a
predetermined slot offset K.sub.0. On the other hand, when the
subcarrier spacings of the data channel and the control channel are
different from each other (8-05,
.mu..sub.PDSCH.noteq..mu..sub.PDCCH), because the slot numbers for
data and control are different from each other, the base station
and the terminal may know that a scheduling offset occurs according
to a predetermined slot offset K.sub.0 based on the subcarrier
spacing of the PDCCH.
[0102] Next, a portion of a decoding process for the PDSCH
scheduled by the DCI in the NR will be described in detail.
[0103] The terminal may receive an indication of a modulation and
coding scheme (MCS) of the PDSCH, together with the frequency and
time resource information allocated for the PDSCH, through the DCI.
An MCS field of the DCI may indicate an index for one table
selected among the following three tables Table 11, Table 12, and
Table 13 through the higher layer. The ranges of indexes indicated
in initial transmission and HARQ retransmission may be different
from each other, wherein indexes 0 to 28 of Table 11, indexes 0 to
27 of Table 12, and indexes 0 to 28 of Table 13 may be used in the
initial transmission and indexes 29 to 31 of Table 11, indexes 28
to 31 of Table 12, and indexes 29 to 31 of Table 13 may be used in
the retransmission. The index indicated in the initial transmission
may contain the modulation order and target code rate information
of the PDSCH transmitted, and the index indicated in the
retransmission may contain the modulation order information of the
PDSCH transmitted.
TABLE-US-00011 TABLE 11 MCS index MCS index table 1 for PDSCH MCS
Index Modulation Order Target code Rate Spectral I.sub.MCS Q.sub.m
R .times. [1024] efficiency 0 2 120 0.2344 1 2 157 0.3066 2 2 193
0.3770 3 2 251 0.4902 4 2 308 0.6016 5 2 379 0.7402 6 2 449 0.8770
7 2 526 1.0273 8 2 602 1.1758 9 2 679 1.3262 10 4 340 1.3281 11 4
378 1.4766 12 4 434 1.6953 13 4 490 1.9141 14 4 553 2.1602 15 4 616
2.4063 16 4 658 2.5703 17 6 438 2.5664 18 6 466 2.7305 19 6 517
3.0293 20 6 567 3.3223 21 6 616 3.6094 22 6 666 3.9023 23 6 719
4.2129 24 6 772 4.5234 25 6 822 4.8164 26 6 873 5.1152 27 6 910
5.3320 28 6 948 5.5547 29 2 reserved 30 4 reserved 31 6
reserved
TABLE-US-00012 TABLE 12 MCS index MCS index table 2 for PDSCH MCS
Index Modulation Order Target code Rate Spectral I.sub.MCS Q.sub.m
R .times. [1024] efficiency 0 2 120 0.2344 1 2 193 0.3770 2 2 308
0.6016 3 2 449 0.8770 4 2 602 1.1758 5 4 378 1.4766 6 4 434 1.6953
7 4 490 1.9141 8 4 553 2.1602 9 4 616 2.4063 10 4 658 2.5703 11 6
466 2.7305 12 6 517 3.0293 13 6 567 3.3223 14 6 616 3.6094 15 6 666
3.9023 16 6 719 4.2129 17 6 772 4.5234 18 6 822 4.8164 19 6 873
5.1152 20 8 682.5 5.3320 21 8 711 5.5547 22 8 754 5.8906 23 8 797
6.2266 24 8 841 6.5703 25 8 885 6.9141 26 8 916.5 7.1602 27 8 948
7.4063 28 2 reserved 29 4 reserved 30 6 reserved 31 8 reserved
TABLE-US-00013 TABLE 13 MCS index MCS index table 3 for PDSCH MCS
Index Modulation Order Target code Rate Spectral I.sub.MCS Q.sub.m
R .times. [1024] efficiency 0 2 30 0.0586 1 2 40 0.0781 2 2 50
0.0977 3 2 64 0.1250 4 2 78 0.1523 5 2 99 0.1934 6 2 120 0.2344 7 2
157 0.3066 8 2 193 0.3770 9 2 251 0.4902 10 2 308 0.6016 11 2 379
0.7402 12 2 449 0.8770 13 2 526 1.0273 14 2 602 1.1758 15 4 340
1.3281 16 4 378 1.4766 17 4 434 1.6953 18 4 490 1.9141 19 4 553
2.1602 20 4 616 2.4063 21 6 438 2.5664 22 6 466 2.7305 23 6 517
3.0293 24 6 567 3.3223 25 6 616 3.6094 26 6 666 3.9023 27 6 719
4.2129 28 6 772 4.5234 29 2 reserved 30 4 reserved 31 6
reserved
[0104] In the case of initial transmission, the terminal may need
to know the size of a transport block (TB) before the scheduled
PDSCH is encoded. For this purpose, the following process may be
performed, and when two TBs are transmitted, the following process
may be performed on each codeword.
[0105] In one embodiment of process 1, the terminal may calculate
the total number of resource elements (REs) allocated for PDSCH
transmission as
N'.sub.RE=N.sub.sc.sup.RBN.sub.symb.sup.sh-N.sub.DMRS.sup.PRB-N.sub.oh-
.sup.PRB in a slot in which a PDSCH is scheduled and one physical
resource block (PRB). In an equation for calculating the total
number of REs allocated for PDSCH transmission, N.sub.sc.sup.RB
indicates "12" corresponding to the number of subcarriers in one
PRB and N.sub.symb.sup.sh indicates the number of symbols scheduled
for the PDSCH in one slot. Also, N.sub.DMRS.sup.PRB indicates the
number of REs allocated for DM-RS in the PRB, which includes the
overhead indicated in the DM-RS CDM groups without data on the DCI.
Also, N.sub.oh.sup.PRB indicates an overhead value indicated by the
higher layer. Next, the total number of REs for the entire
scheduled PRB is calculated as
N.sub.RE=min(156,N'.sub.RE)n.sub.PRB, and in an equation for
calculating the total number of REs for the entire scheduled PRB,
n.sub.PRB indicates the total number of PRBs allocated for PDSCH
transmission to the terminal.
[0106] In one embodiment of process 2, the intermediate number of
information bits in the PDSCH may be calculated as
N.sub.info=N.sub.RERQ.sub.mv, where R and Q.sub.m indicate a target
rate and a modulation order indicated by the MCS, respectively, and
"v" indicates the number of layers.
[0107] In one embodiment of process 3, when the calculated
N.sub.info value is greater than 3824, the terminal may determine
that a plurality of code blocks may be transmitted (process 5), and
otherwise, the terminal may determine that a single code block is
transmitted (process 4).
[0108] In one embodiment of process 4, when the terminal determines
that a single code block is transmitted, the terminal may
calculate
N info ' = max ( 24 , 2 n N info 2 n ) , ##EQU00004##
where n=max(3,.left brkt-bot.log.sub.2(N.sub.info).right
brkt-bot.-6), and then find a minimum transport block size (TBS)
not smaller than N'.sub.info in Table 14. The TBS found by the
terminal may be the size of a transport block (TB) determined by
the terminal.
[0109] In one embodiment of process 5, when the terminal determines
that a plurality of code blocks may be transmitted, the terminal
may perform the following process according to
N info ' = max ( 3840 , 2 n .times. round ( N info - 24 2 n ) ) ,
##EQU00005##
where n=.left brkt-bot.log.sub.2(N.sub.info-24).right brkt-bot.-5,
a value, and a target code rate.
[0110] In one example of process 5-1, when the target code
rate.ltoreq.1/4,
TBS = 8 C N info ' + 24 8 C - 24 , ##EQU00006##
where
C = N info ' + 24 3816 , ##EQU00007##
and the calculated TBS indicates the number of code blocks.
[0111] In one example of process 5-2, when the target code
rate>1/4, when N'.sub.info>8424,
TBS = 8 C N info ' + 24 8 C - 24 , ##EQU00008##
where
C = N info ' + 24 8424 , ##EQU00009##
and the calculated TBS indicates the number of code blocks.
Otherwise,
TBS = 8 N info ' + 24 8 - 24 , ##EQU00010##
and a single code block is transmitted.
TABLE-US-00014 TABLE 14 Index and TBS Index TBS 1 24 2 32 3 40 4 48
5 56 6 64 7 72 8 80 9 88 10 96 11 104 12 112 13 120 14 128 15 136
16 144 17 152 18 160 19 168 20 176 21 184 22 192 23 208 24 224 25
240 26 256 27 272 28 288 29 304 30 320 31 336 32 352 33 368 34 384
35 408 36 432 37 456 38 480 39 504 40 528 41 552 42 576 43 608 44
640 45 672 46 704 47 736 48 768 49 808 50 848 51 888 52 928 53 984
54 1032 55 1064 56 1128 57 1160 58 1192 59 1224 60 1256 61 1288 62
1320 63 1352 64 1416 65 1480 66 1544 67 1608 68 1672 69 1736 70
1800 71 1864 72 1928 73 2024 74 2088 75 2152 76 2216 77 2280 78
2408 79 2472 80 2536 81 2600 82 2664 83 2728 84 2792 85 2856 86
2976 87 3104 88 3240 89 3368 90 3496 91 3624 92 3752 93 3824
[0112] In the case of retransmission, it is assumed that the TB
size of a PDSCH to be retransmitted is the same as the TB size
calculated in the initial transmission.
[0113] FIG. 9 illustrates a method of determining a low-density
parity-check (LDPC) base graph (BG) used for encoding of a
transport block (TB) and decoding of a codeword in a wireless
communication system according to an embodiment of the
disclosure.
[0114] Referring to FIG. 9, a method of selecting an LDPC BG is
illustrated. The terminal may find an LDPC BG for decoding the
corresponding code word according to the target code rate indicated
by the MCS and the calculated TB size. In the NR, one of BG1 and
BG2 may be selected as in FIG. 9 according to the TB size and the
code rate. In the case of BG1, the length of a code block may be
determined as 8448, and in the case of BG2, the length of a code
block 0 may be determined as 3840. In case of initial transmission,
the terminal may simultaneously find the LDPC BG in calculating the
TB size according to the situation. For example, when the above TB
size calculation process 5-1) is applied, the terminal may find
that the LDPC BG2 is used, and when the TB size calculation process
5-2) is applied, the terminal may find that the LDPC BG1 is used.
In case of retransmission, the LDPC BG retransmitted may be assumed
to be equal to the LDPC BG used in the initial transmission.
[0115] Next, the terminal may find data through processes such as
de-interleaving, de-ratematching, and decoding of the received
codeword according to the found TB size, the BG, and the like. In
case of retransmission, the terminal may combine and then decode
the received signal received in the initial transmission and the
received signal received in the retransmission into a buffer
corresponding to the LDPC BG and the TB size used in the initial
transmission and the retransmission, thereby improving the
reception reliability.
[0116] When the TB is transmitted in a plurality of code blocks,
the terminal may retransmit only some of the code blocks in order
to improve the retransmission efficiency, and in this case, the
unit of code blocks retransmitted may be referred to as a code
block group (CBG). When the terminal supports CBG transmission, the
number of CBGs of the TB received by the terminal may be determined
by the following equation.
M=min (N, C).
[0117] In the above equation, N is a value configured to the higher
layer and C is the number of code blocks transmitted. Among a total
of M CBGs, the (m=0, 1, . . . , M.sub.1-1, M.sub.1=mod (C, M))th
CBG may include the (m+K.sub.1+k, k=0, 1, . . . , K.sub.1-1,
K.sub.1=[C/M])th code blocks and the (m=M.sub.1, M.sub.1+1, . . . ,
M-1)th CBG may include the (M.sub.1K.sub.1+(m-M.sub.1)K.sub.2+k,
k=0, 1, . . . , K.sub.2-1, K.sub.2=[C/M])th code blocks.
[0118] When receiving the CBG through the above configuration, the
terminal may generate an ACK/NACK for each CBG and then generate a
HARQ-ACK codebook and transmit the same to the base station. After
receiving the HARQ-ACK information, the base station may perform
retransmission in units of CBG and may notify the index of a
retransmitted CBG to the terminal through the DCI. A DCI field in
which the CBG index is transmitted may be a CBG transmission
information field described above.
[0119] FIG. 10 illustrates an example of slot-by-slot repeated
transmission (slot aggregation) in a wireless communication system
according to an embodiment of the disclosure.
[0120] Referring to FIG. 10, in the NR, repeated transmission of
the same PDSCH may be supported to improve the PDSCH reception
reliability of the terminal (10-00). The base station may set the
number of times of repeated transmissions of the PDSCH, for
example, pdsch-AggregationFactor in PDSCH-Config to the higher
layer such as RRC, and when the number of times of repeated
transmissions is configured, the PDSCH scheduled in the DCI may be
repeatedly transmitted in as many slots as the number of
consecutive repeated transmissions (10-05). All the PDSCHs
repeatedly transmitted may be allocated the same time resource in a
slot, and as illustrated in FIG. 7, it may be an OFDM symbol start
position 7-00 and a length 7-05 in one slot indicated by the DCI.
Also, it may be assumed that the same transport block (TB) is
transmitted in all the PDSCHs repeatedly transmitted. The terminal
may expect that the repeatedly transmitted PDSCH is transmitted
only in a single layer. Also, as in Table 15 below, a redundancy
version (RV) of the repeatedly transmitted PDSCH may be determined
according to an RV value indicated in the DCI for scheduling the
PDSCH and an index of the repeatedly transmitted PDSCH.
TABLE-US-00015 TABLE 15 RV of the repeatedly transmitted PDSCH
rv.sub.id indicated by rv.sub.id to be applied to n.sup.th
transmission occasion the DCI scheduling n mod n mod n mod n mod
the PDSCH 4 = 0 4 = 1 4 = 2 4 = 3 0 0 2 3 1 2 2 3 1 0 3 3 1 0 2 1 1
0 2 3
[0121] In Table 15, "n" may indicate an index of each PDSCH within
the number of times of repeated transmission determined as the
higher layer (10-10, 10-15).
[0122] Referring to the above descriptions related to the above DCI
structure, the PDSCH time/frequency resource allocation, and the
PDSCH transmission and reception procedure performed based thereon,
in LTE standard specification, the NR may use only a single
transmission point/panel/beam in repeated transmission of the
PDSCH. When cooperative communication using a plurality of
transmission points/panels/beams may be applied in PDSCH repeated
transmission, because more robust performance may be obtained
against a channel blockage or the like, a repeated transmission
scheme based on a plurality of transmission points/panels/beams is
actively discussed in the NR standard specification.
[0123] In this case, in order to improve the reception reliability
of the terminal, it may be necessary to combine transmission and
reception points (TRPs)/beam-by-beam transmission signals. When
different codewords are transmitted for each TRP/beam, all of the
LDPC BGs used for encoding/decoding in addition to the TB size for
each codeword may need to be equal for combining. As described
above, the terminal may find the TB size for the codeword and the
LDPC BG from the MCS and the scheduled RE amount indicated through
the DCI, and when the TRP/beam-by-beam rate matching patterns are
applied differently, the TB sizes and/or LDPC BGs for each codeword
calculated by the terminal may be different and accordingly,
combining may not be performed. Thus, the disclosure provides a
method of improving the reception reliability by ensuring that the
terminal performs decoding after matching the TB size and the LDPC
BG of the TRP/beam-by-beam codeword.
[0124] Hereinafter, embodiments of the disclosure will be described
in detail with the accompanying drawings. In the following
description of the disclosure, detailed descriptions of well-known
functions or configurations maybe omitted because they would
unnecessarily obscure the subject matters of the disclosure. Also,
terms to be described below may be terms defined considering
functions in the disclosure and may vary according to users' or
operators' intentions or practices. Therefore, the definition
thereof should be made based on the contents throughout the
specification.
[0125] Hereinafter, a base station may be an agent performing
terminal resource allocation and may be at least one of a gNode B,
a gNB, an eNode B, a Node B, a base station (BS), a radio access
unit, a base station controller, or a node on a network. Examples
of a terminal may include a user equipment (UE), a mobile station
(MS), a cellular phone, a smartphone, a computer, or a multimedia
system capable of performing a communication function. Also,
although embodiments of the disclosure will be described below by
using an NR or LTE/LTE-A system as an example, the embodiments of
the disclosure may also be applied to other communication systems
having similar technical backgrounds or channel forms. Also, the
embodiments of the disclosure may also be applied to other
communication systems through some modifications without departing
from the scope of the disclosure by the judgment of those of
ordinary skill in the art.
[0126] The description in the disclosure may be applied to FDD and
TDD systems.
[0127] In the disclosure, higher layer signaling may be a method of
transmitting signals from the base station to the terminal by using
a downlink data channel of the physical layer or from the terminal
to the base station by using an uplink data channel of the physical
layer, and may also be referred to as RRC signaling, PDCP
signaling, or MAC CE.
[0128] Hereinafter, in the disclosure, in order to determine
whether to apply cooperative communication, the terminal may use
various methods in which one or more PDCCHs for allocating the
PDSCH to which cooperative communication is applied have a
particular format, one or more PDCCHs for allocating the PDSCH to
which cooperative communication is applied include a particular
indicator indicating whether to apply cooperative communication,
one or more PDCCHs for allocating the PDSCH to which cooperative
communication is applied are scrambled with a particular RNTI, or
cooperative communication application is assumed in a particular
interval indicated by the higher layer. Hereinafter, for
convenience of description, a case where the terminal receives a
PDSCH to which cooperative communication is applied based on
conditions similar to those described above maybe referred to as an
NC-JT case.
[0129] Hereinafter, in the disclosure, determining the priority
between A and B may be variously referred to as selecting a higher
priority according to a predetermined priority rule and performing
an operation corresponding thereto or omitting or dropping an
operation with respect to having a lower priority.
[0130] Hereinafter, in the disclosure, the above examples will be
described through a plurality of embodiments of the disclosure;
however, they are not independent of each other and one or more
embodiments of the disclosure may be applied simultaneously or in
combination.
Embodiment 1: DCI Reception for NC-JT
[0131] Unlike the existing systems, 5G wireless communication
systems may support not only services requiring high transmission
rates but also services having very short transmission delays and
services requiring high connection density. In a wireless
communication network including a plurality of cells, TRPs, or
beams, cooperative communication (coordinated transmission) between
each cell, TRP, and/or beam may be an elementary technology for
increasing the strength of a signal received by the terminal or
efficiently performing each cell, TRP, and/or inter-beam
interference control to satisfy various service requirements.
[0132] Joint transmission (JT) may be a representative transmission
technology for the above cooperative communication and may increase
the strength of a signal received by the terminal by supporting one
terminal through different cells, TRPs, and/or beams based on the
joint transmission technology. Meanwhile, because the
characteristics of the channels between the cells, TRPs, and/or
beams may be significantly different, it may be necessary to apply
different precoding, MCS, or resource allocation to the links
between the cells, TRPs, and/or beams. Particularly, in a case of
non-coherent joint transmission (NC-JT) supporting non-coherent
precoding between the cells, TRPs, and/or beams, individual
downlink (DL) transmission information settings for the cells,
TRPs, and/or beams may be important. Meanwhile, such individual DL
transmission information configuration for the cells, TRPs, and/or
beams may be a main factor to increase the payload required for DL
DCI transmission, which may adversely affect the reception
performance of the PDCCH for transmitting the DCI. Thus, it may be
necessary to carefully design a tradeoff between the DCI
information amount and the PDCCH reception performance for JT
support.
[0133] FIG. 11 illustrates an example of antenna port configuration
and resource allocation for cooperative communication in a wireless
communication system according to an embodiment of the
disclosure.
[0134] Referring to FIG. 11, examples of a joint transmission (JT)
technique and radio resource allocation for each TRP according to
the situation are illustrated. In FIG. 11, 11-00 is an example of
coherent joint transmission (C-JT) supporting coherent precoding
between the cells, TRPs, and/or beams. In the C-JT, single data
(PDSCH) is transmitted from a TRP A 11-05 and a TRP B 11-10 to a
terminal 11-15, and joint precoding is performed in a plurality of
TRPs. This means that the TRP A 11-05 and the TRP B 11-10 transmit
the same DMRS ports (e.g., DMRS ports A and B in both TRPs) for
receiving the same PDSCH. In this case, the terminal may receive
one piece of DCI information for receiving one PDSCH demodulated by
the DMRS ports A and B.
[0135] In FIG. 11, 11-20 is an example of non-coherent joint
transmission (NC-JT) supporting non-coherent precoding between the
cells, TRPs, and/or beams. In the case of the NC-JT, a PDSCH may be
transmitted to a terminal 11-35 for each cell, TRP, and/or beam,
and individual precoding may be applied to each PDSCH. The cells,
TRPs, and/or beams may transmit different PDSCHs to improve the
throughput with respect to the single cell, TRP, and/or beam
transmissions, or the cells, TRPs, and/or beams may repeatedly
transmit the same PDSCH to improve the reliability the single cell,
TRP, and/or beam transmission.
[0136] As in the case where the frequency and time resources used
by multiple TRPs for PDSCH transmission are all the same (11-40),
the case where the frequency and time resources used by multiple
TRPs do not overlap at all (11-45), and the case where the
frequency and time resources used by multiple TRPs overlap
partially (11-50), various radio resource allocations may be
considered. When multiple TRPs repeatedly transmit the same PDSCH
in each case for the above radio resource allocation, when a
receiving terminal does not know whether the PDSCH is repeatedly
transmitted, the terminal may not perform combining in the physical
layer for the PDSCH and thus there may be a limitation in improving
the reliability. Therefore, the disclosure provides a repeated
transmission indication and configuration method for improving the
NC-JT transmission reliability.
[0137] Various forms, structures, and relations of DCIs may be
considered to simultaneously allocate multiple PDSCHs to one
terminal for NC-JT support.
[0138] FIG. 12 illustrates an example of a DCI configuration for
cooperative communication in a wireless communication system
according to an embodiment of the disclosure. Referring to FIG. 12,
four examples of the DCI design for NC-JT support are
illustrated.
[0139] In FIG. 12, a case #1 12-00 is an example in which control
information about the PDSCH transmitted in (N-1) additional TRPs is
transmitted in the same format (same DCI format) as control
information about the PDSCH transmitted in a serving TRP, in a
situation where (N-1) different PDSCHs are transmitted in (N-1)
additional TRPs (TRP #1 to TRP # (N-1)) in addition to a serving
TRP (TRP #0) used in single PDSCH transmission. That is, the
terminals may acquire control information about the PDSCHs
transmitted in different TRPs (TRP #0 to TRP # (N-1)) through the
DCIs having the same DCI format and the same payload. In the case
#1 described above, each PDSCH control (allocation) freedom degree
may be completely ensured; however, when each DCI is transmitted in
different TRPs, a DCI-by-DCI coverage difference may occur and thus
the reception performance may degrade.
[0140] In FIG. 12, a case #2 12-05 is an example in which control
information about the PDSCH transmitted in (N-1) additional TRPs is
transmitted in a different format (different DCI format or
different DCI payload) than control information about the PDSCH
transmitted in a serving TRP, in a situation where (N-1) different
PDSCHs are transmitted in (N-1) additional TRPs (TRP #1 to TRP #
(N-1)) in addition to a serving TRP (TRP #0) used in single PDSCH
transmission. For example, in the case of DCI #0 for transmitting
control information about the PDSCH transmitted in a serving TRP
(TRP #0), all of the information elements of a DCI format 1_0 or a
DCI format 1_1 may be included, but in case of "shortened" DCIs
(sDCI #0 to sDCI # (N-2)) for transmitting control information
about the PDSCHs transmitted in cooperative TRPs (TRP #1 to TRP #
(N-1)), only some of the information elements of the DCI format 1_0
or the DCI format 1_1 may be included. Thus, in the case of sDCI
for transmitting control information about the PDSCHs transmitted
in the cooperative TRP, the payload may be smaller than that of the
normal DCI (nDCI) for transmitting PDSCH-related control
information transmitted in the serving TRP or as many reserved bits
as the number of bits insufficient in comparison with the nDCL may
be included. In the case #2 described above, each PDSCH control
(allocation) freedom degree may be restricted according to the
contents of information elements included in the sDCI; however,
because the reception performance of the sDCI may be higher that of
the nDCI, the probability of occurrence of a DCI-by-DCI coverage
difference may decrease.
[0141] In FIG. 12, a case #3 12-10 is another example in which
control information about the PDSCH transmitted in (N-1) additional
TRPs is transmitted in a different format (different DCI format or
different DCI payload) than control information about the PDSCH
transmitted in a serving TRP, in a situation where (N-1) different
PDSCHs are transmitted in (N-1) additional TRPs (TRP #1 to TRP #
(N-1)) in addition to a serving TRP (TRP #0) used in single PDSCH
transmission. For example, in the case of DCI #0 for transmitting
control information about the PDSCH transmitted in a serving TRP
(TRP #0), all of the information elements of a DCI format 1_0 or a
DCI format 1_1 may be included, and in case of control information
about the PDSCHs transmitted in cooperative TRPs (TRP #1 to TRP #
(N-1)), only some of the information elements of the DCI format 1_0
or the DCI format 1_1 may be collected and transmitted in one piece
of "secondary" DCI (sDCI). For example, the sDCI may have at least
one piece of information among HARQ-related information such as
frequency-domain resource allocation (assignment) and time-domain
resource allocation (assignment) of the cooperative TRPs. In
addition, in case of information not included in the sDCI, such as
a BWP indicator or a carrier indicator, it may follow the DCI (DCI
#0, normal DCI, nDCI) of the serving TRP. In the case #3, each
PDSCH control (allocation) freedom degree may be restricted
according to the contents of information elements included in the
sDCI, but the reception performance of the sDCI may be adjusted and
the complexity of DCI blind decoding of the terminal may be reduced
in comparison with the case #1 or the case #2.
[0142] In FIG. 12, a case #4 12-15 is an example in which control
information about the PDSCH transmitted in (N-1) additional TRPs is
transmitted in the same DCI (long DCI, IDCI) as control information
about the PDSCH transmitted in a serving TRP, in a situation where
(N-1) different PDSCHs are transmitted in (N-1) additional TRPs
(TRP #1 to TRP # (N-1)) in addition to a serving TRP (TRP #0) used
in single PDSCH transmission. That is, the terminal may acquire
control information about the PDSCHs transmitted in different TRPs
(TRP #0 to TRP # (N-1)) through single DCI. In the case #4, the
complexity of DCI blind decoding of the terminal may not increase,
but the PDSCH control (allocation) freedom degree may be low such
that the number of cooperative TRPs may be restricted according to
the long DCI payload restriction.
[0143] In the following description and embodiments of the
disclosure, the sDCI may refer to various auxiliary DCIs such as a
shortened DCI, a secondary DCI, or a normal DCI (the DCI format 1_0
or 1_1 described above) including PDSCH control information
transmitted in the cooperative TRP, and unless otherwise specified,
the description may be similarly applicable to the various
auxiliary DCIs.
[0144] In the following description and embodiments of the
disclosure, the above case #1, case #2, and case #3 in which one or
more DCIs (PDCCHs) are used for NC-JT support may be classified as
multiple PDCCH-based NC-JT, the above case #4 in which single DCI
(PDCCH) is used for NC-JT support may be classified as single
PDCCH-based NC-JT.
[0145] In embodiments of the disclosure, "cooperative TRP" may be
replaced with various terms such as "cooperative panel" or
"cooperative beam" in actual application.
[0146] In embodiments of the disclosure, "the case where NC-JT is
applied" may be interpreted variously according to situations, such
as "the case where the terminal receives one or more PDSCHs
simultaneously in one BWP," "the case where the terminal
simultaneously receives the PDSCH based on two or more transmission
configuration indicator (TCI) indications simultaneously in one
BWP," and "the case where the PDSCH received by the terminal is
associated with one or more DMRS port groups," but it is used as
one expression for convenience of description.
[0147] In the disclosure, a radio protocol architecture for the
NC-JT may be variously used according to TRP deployment scenarios.
For example, when there is no or small backhaul delay between the
cooperative TRPs, an architecture based on MAC layer multiplexing
may be used (CA-like method). On the other hand, when the backhaul
delay between cooperative TRPs is not negligible (e.g., when a time
of 2 ms or more is required for CSI exchange or scheduling
information exchange between the cooperative TRPs), the
characteristics robust against delays may be secured by using an
independent structure for each TRP from the RLC layer (DC-like
method).
Embodiment 2: NC-JT Repeated Transmission Configuration Method
[0148] In the present embodiment of the disclosure, a detailed
configuration and indication method for repeatedly transmitting the
same PDSCH, in which two or more TRPs are equal to each other,
described in Embodiment 1, in the same transmission band, for
example, a transmission band, a component carrier, a BWP, or the
like, are provided.
[0149] FIGS. 13A to 13D illustrate examples of repeated
transmission of multiple TRPs based on various resource allocation
methods in a wireless communication system according to an
embodiment of the disclosure. FIGS. 13A to 13D illustrate examples
in which two or more TRPs repeatedly transmit the same PDSCH.
[0150] In the current NR, as described above, as many slots as the
number of times of repeated transmission may be required in the
repeated transmission of the same PDSCH and the same cell, TRP,
and/or beam may be used in each repeated transmission. On the other
hand, through an embodiment of the disclosure described herein, the
higher reliability may be achieved by using different TRPs for
repeated transmissions in each slot (13-00, 13-05). Meanwhile,
other repeated transmission methods may be used according to the
terminal capability, the delay time requirement, the available
resource state between TRPs, or the like. For example, when the
terminal has the capability to receive NC-JT, each TRP may increase
the frequency resource utilization rate and reduce the delay time
required for PDSCH decoding by using a method of transmitting the
same PDSCH in the same time and frequency resources (13-10, 13-15).
The method may be efficient when the inter-TRP beams to be
simultaneously transmitted are nearly orthogonal to each other and
thus there is small inter-beam interference. As another example,
each TRP may use a method of transmitting the same PDSCH at the
same time and in the non-overlapping frequency resources (13-20,
13-25). The method may be efficient when the inter-beam
interference of TRPs to be simultaneously transmitted is large and
the available frequency resources of each TRP are large. As another
example, each TRP may use a method of transmitting the same PDSCH
on different OFDM symbols in the same slot (13-30, 13-35). The
method may be efficient when there are not many available frequency
resources of each TRP and the size of data to be transmitted is
small. In addition to the above methods, modifications based on the
above methods may be possible.
[0151] In the above methods, single DCI may be used to schedule
repeated transmission (13-00, 13-10, 13-20, 13-30), and the DCI may
indicate a list of all TRPs to participate in the repeated
transmission. The list of TRPs to be repeatedly transmitted may be
indicated in the form of a TCI state list, and the length of the
TCI state list may change dynamically. The DCI may be repeatedly
transmitted to improve the reliability, and different beams may be
applied to each DCI in the repeated transmission. Alternatively,
multiple DCI may be used to schedule repeated transmission (13-05,
13-15, 13-25, 13-35), and each DCI may correspond to the PDSCH of
different TRPs to participate in the repeated transmission. The TRP
for each DCI may be indicated in the form of a TCI state or a
resource used in repeated transmission, and a detailed description
thereof will be given in embodiments of the disclosure to be
described below. Alternatively, shortened DCI may be used to
schedule repeated transmission, and each of normal DCI and
secondary DCI may correspond to the PDSCH of different TRPs to
participate in the repeated transmission. The above indication
method may be commonly applied to both the repeated transmission
through multiple TRPs and the transmission of different data
through multiple TRPs.
[0152] As for the above repeated transmission method, all TRPs may
transmit a single codeword or transmit an independent codeword for
each TRP. In the latter case, because different MCS and/or RV
values may be determined for each codeword, more adaptive
transmission may be possible than the former case. In the case of
transmitting an independent codeword for each TRP, the terminal may
perform the following process for each codeword for codeword
decoding. Each of the following processes may be the same as the
above process for single codeword decoding in the existing NR: 1)
Calculation of TB size through the number of REs, MCS, or the like
corresponding to the resource where the codeword is transmitted;
and 2) Determination of LDPC BG from TB size and target code
rate.
[0153] The parameters used in the above process may mean the
following: (1) N.sub.RE: The total number of REs allocated in PDSCH
schedule. The total number of REs allocated in the PDSCH schedule
may be calculated based on the number of REs rate-matched by the
above frequency-axis RB resource allocation information, the
time-axis symbol resource allocation information, rate matching
pattern information indicated through the higher layer and/or the
DCI, zero power channel state information reference signal
(ZP-CSI-RS) configuration information, RS configuration information
such as DMRS and nonzero power channel state information reference
signal (NZP-CSI-RS), LTE-CRS-ToMatchAround configuration
information, or the like; (2) R: Target code rate indicated by MCS;
(3) Q.sub.m: Modulation order indicated by MCS; and (4) v: The
number of layers indicated by antenna port field of DCI or the
like.
[0154] In this case, each of N.sub.RE, R, Q.sub.m, and v parameters
for the repeatedly transmitted codeword or each of scheduling
parameters for calculating N.sub.RE, R, Q.sub.m, and v parameters
(e.g., the parameters indicated by the above frequency-axis
resource allocation method and the parameters indicated by the
time-axis resource allocation method) may be individually indicated
for each codeword or one value may be indicated for all repeated
transmission.
[0155] When one value is indicated for each parameter, the value
indicated for each parameter may be applied as is to all repeated
transmission codewords according to the repeated transmission
technique and the base station configuration or the value modified
according to a particular rule or equation may be applied for each
repeated transmission codeword. For example, when a codeword for
each TRP is repeatedly transmitted in different time resources
(13-00, 13-05, 13-30, and 13-35), the same frequency-axis resource
allocation as that indicated by the DCI may be applied to each
codeword. Alternatively, when the codeword for each TRP is
repeatedly transmitted in different frequency-axis resources
(13-20, 13-25), non-overlapping frequency-axis resource allocation
may be applied according to a particular rule for each codeword.
For example, when two repeated transmission codewords are
scheduled, the even-numbered precoding group (PRG) in the
frequency-axis resource allocation indicated by the DCI may be
allocated to the first codeword and the odd-numbered PRG may be
allocated to the second codeword. In a case where the size of the
PRG is configured to wideband, when the number of RBs allocated by
frequency-axis resource allocation is N_RB, the first .left
brkt-bot.N.sub.RB/2.right brkt-bot. RBs may be allocated to the
first codeword and the other .left brkt-bot.N.sub.RB/2.right
brkt-bot. RBs may be allocated to the second codeword. In summary,
it may be as in Table 16.
TABLE-US-00016 TABLE 16 Allocation of a number of RBs Comb-like
frequency resource allocation between/among TRPs. For wideband PRG,
first [N_RB/2] RBs are assigned to TCI state 1 and the remaining [N
RB/2] RBs are assigned to TCI state 2, For PRG size-2 or 4, even
PRGs within the allocated FDRA are assigned to TCI State 1 and odd
PRGs within the allocated FDRA are assigned to TCI state 2
[0156] As another example, when the codeword for each TRP is
repeatedly transmitted in different frequency-axis resources
(13-20, 13-25) or when the codeword for each TRP is repeatedly
transmitted in different symbols (13-00, 13-05)), a symbol offset S
(7-00) and a symbol length L (7-05) in the time-axis resource
allocation indicated by the DCI may be equally applied to each
codeword. Meanwhile, when the codeword for each TRP is repeatedly
transmitted in different symbols in the slot (13-30, 13-35), a
symbol offset S (7-00) and a symbol length L (7-05) in the
time-axis resource allocation indicated by the DCI may be applied
to the first codeword and L (7-05) may be equally applied as the
symbol length to the second codeword but S'=S+L may be applied as
the symbol offset. Also, L (7-05) may be equally applied as the
symbol length to the nth codeword among the repeatedly transmitted
TRP codewords, but S''=S+(n-1)L may be applied as the symbol
offset.
[0157] When the rate matching pattern is different for each
codeword, different amounts of RE resources are allocated, or
different MCS values are configured, the TB sizes calculated for
each codeword and the determined LDPC BGs may be different from
each other. In this case, combining between codewords, for
different TB sizes and LDPC BGs, may not be performed, and thus it
may be difficult to achieve the target reception reliability in the
terminal.
[0158] Thus, in order to achieve the target reception reliability
of the terminal, it may be necessary to ensure the same TB size and
the same LDPC BG between the codewords repeatedly transmitted for
each TRP and the following method may be considered for this
purpose.
[0159] In one example of method 1, the base station performs
scheduling such that the TB sizes and LDPC BGs of all codewords may
be equal to each other.
[0160] In one example of method 2, the terminal configures a
representative value for TB size and LDPC BG calculation in
repeated transmission.
[0161] A detailed description of each method described above will
be described in the following embodiment.
Embodiment 3: Base Station Perform Scheduling such that the TB
Sizes and LDPC BGs of All Codewords are the Same
[0162] The base station may previously know what TB size and LDPC
BG values are to be calculated by the terminal with respect to the
repeatedly transmitted codeword for each TRP. As described above,
the TB to be calculated by the terminal may be obtained by the
intermediate number of information bit N.sub.info=N.sub.RERQ.sub.mv
in the PDSCH, each element of the intermediate number of
information bit may be the same as that described above.
[0163] The base station may configure constraint conditions on at
least one of four elements of the above intermediate number of
information bits per TRP/codeword in order for the terminal to
obtain the same TB size for the codeword transmitted for each TRP.
For example, the base station may configure, as the constraint
condition, the case where the N.sub.RE value for each TRP/codeword
is equal, the frequency and time-axis resource allocation
information is equal, the rate matching pattern or the number of
rate-matched REs is equal, the MCS is equal, or the number of
layers is equal. Also, two or more of the above constraints may be
combined. Alternatively, even when the above constraint condition
is not applied, a combination of N.sub.RE, R, Q.sub.m, and v values
may be configured such that the TB size calculated by the terminal
for each TRP/codeword may be equal. Meanwhile, the terminal may not
expect that the TB size calculated for each TRP/codeword maybe
different, for combining.
[0164] As described above, the LDPC BG may be determined by the
terminal through the TB size calculated by the terminal and the
target code rate indicated by the MCS. The base station may
configure constraint conditions on the TB size and/or MCS such that
the LDPC BG found by the terminal for each TRP/codeword may be
equal. For example, the constraint condition may be configured as
described above such that that the TB size per TRP/codeword may be
equal, and the constraint condition may be configured such that the
MCS may be equal. Alternatively, even when the above constraint
condition is not applied, a combination of TB size and MCS may be
configured such that the TB size found by the terminal for each
TRP/codeword may be equal. Meanwhile, the terminal may not expect
that the LDPC BG calculated for each TRP/codeword maybe different,
for combining.
[0165] According to the present embodiment of the disclosure, the
change in the terminal for matching the TB size and LDPC BG per
TRP/codeword may be small, but the constraint on the codeword
schedule and transmission for each TRP in the base station may be
large.
Embodiment 4: Configure Representative Value for Calculating TB
Size and LDPC BG in Terminal in Repeated Transmission
[0166] In Embodiment 3 described above, even when the channel state
for each TRP or the amount of resources allocatable to the PDSCH is
different, flexible resource allocation/MCS allocation may be
difficult due to the above constraint conditions. On the other
hand, in the present embodiment of the disclosure, the base station
may schedule the repeated transmission PDSCH more flexibly
considering the channel state for each TRP or the amount of
available resources and the terminal may configure a representative
value for calculating the TB size and LDPC BG with respect to the
repeatedly transmitted codeword for each TRP, thereby making it
possible to obtain the same TB size and LDPC BG for all
codewords.
[0167] With respect to the repeatedly transmitted codeword for each
TRP, a representative value for calculating the TB size and LDPC BG
may be obtained from the TB size calculated for each codeword. For
example, the TB size of the codeword for each TRP may be calculated
according to the TB size calculation method in the NR described
above and then the representative value of these TB sizes may be
used for combining and decoding. When a total of N TB sizes of the
codeword for each TRP are TBS.sub.1, TBS.sub.2, . . . , TBS.sub.N,
the representative value of the TB size may be represented by a
function such as TBS=f(TBS.sub.1, TBS.sub.2, . . . , TBS.sub.N) and
the following function may be considered as a function for
calculating the TBS.
[0168] In one example of maximum value, f(TBS.sub.1, TBS.sub.2, . .
. , TBS.sub.N)=max(TBS.sub.1, TBS.sub.2, . . . , TBS.sub.N). When
the TB size of the codeword for each TRP is different, the TBS may
be calculated based on the largest TB size. In this case, because
the effective code rate is high, it may be efficient in terms of
the throughput.
[0169] In one example of minimum value, f(TBS.sub.1, TBS.sub.2, . .
. , TBS.sub.N)=min(TBS.sub.1, TBS.sub.2, . . . , TBS.sub.N). When
the TB size of the codeword for each TRP is different, the TBS may
be calculated based on the smallest TB size. In this case, because
the effective code rate is low, high reliability may be
obtained.
[0170] In one example of average value, f(TBS.sub.1, TBS.sub.2, . .
. , TBS.sub.N)=(TBS.sub.1, TBS.sub.2, . . . , TBS.sub.N)/N. When
the TB size of the codeword for each TRP is different, the TBS may
be calculated based on the average value of the TB size.
[0171] In addition to the above functions, various functions may be
considered as a function for TBS calculation. Alternatively, in
order to reduce the calculation complexity of the terminal, instead
of calculating all TB sizes for each codeword, the TB size for one
codeword expected to have the largest or smallest TB size may be
configured as a representative TB size and the terminal may
calculate only the representative TB size. For example, when the
MCS of the codeword for each TRP may be configured differently, the
TB size corresponding to the codeword of the highest or lowest MCS
may be set as a representative TB size. Alternatively, when the
frequency/time-axis resource allocation of the codeword for each
TRP may be configured differently, the TB size corresponding to the
codeword to which the largest or smallest frequency resource/time
resource/RE number is allocated may be configured as a
representative TB size. A representative LDPC BG value may be
obtained in the MCS corresponding to the representative TB size and
the corresponding codeword.
[0172] Alternatively, the number of TBs may be determined based on
the number of REs allocated to all codewords repeatedly
transmitted. For example, when one frequency-axis resource
allocation and time-axis resource allocation are indicated for the
entire repeated transmission as described above, the N.sub.RE value
according to the frequency-axis and time-axis resource allocation
may be calculated and the representative TB size TBS.sub.rep may be
obtained from the calculated N.sub.RE value. In this case, the same
MCS and the number of layers may be indicated or applied to all the
codewords repeatedly transmitted; that is, all of R, Q.sub.m, and v
of the repeatedly transmitted codeword may be equal. The TB size of
each codeword repeatedly transmitted may be configured based on the
representative TB size; for example, it may be set as at least as
one of the following: TB size for each codeword is equal to the
representative TB size, i.e., TBS.sub.1=TBS.sub.2=. . .
=TBS.sub.N=TBS.sub.rep; TB size for each codeword is equal to a
value obtained by dividing the representative TB size by the number
of repeatedly transmitted codewords, i.e.,
TBS.sub.1=TBS.sub.2=. . . =TBS.sub.N=.left
brkt-top.TBS.sub.rep/N.right brkt-bot. or
TBS.sub.1=TBS.sub.2=. . . =TBS.sub.N=.left
brkt-bot.TBS.sub.rep/N.right brkt-bot.
[0173] Alternatively, a representative TRP for obtaining the
representative value of the TB size may be configured. For example,
in the case of repeated transmission at TRP.sub.1, TRP.sub.2, . . .
, TRP.sub.N, the terminal may configure the TB size calculated from
the codeword transmitted at TRP.sub.x(1.ltoreq.x.ltoreq.N), as the
representative TB size. For convenience of description, the
TRP.sub.x maybe referred to as a representative TRP. Meanwhile, the
terminal may fail to directly receive the instruction of
information about the transmission TRP in the repeated
transmission, and in this case, the terminal may implicitly
configure the representative TRP through at least one of the
following methods or a combination thereof.
[0174] In one example of method 1 of TCI state, two or more TCI
states may be simultaneously activated for one PDSCH through
DCI/MAC-CE or the like, wherein each of these TCI states may
correspond to channel/beam information for each TRP used for
repeated transmission. Thus, a particular TCI state may be used as
the representative TRP. That is, the representative TB size may be
calculated from the codeword corresponding to the particular TCI
state. The particular TCI state may be, for example, the
lowest/highest TCI state index or the first/last TCI state index
among the activated TCI states.
[0175] In one example of method 2 of codeword index, when two
codewords are scheduled in the DCI, each codeword may be
interpreted as a codeword repeatedly transmitted when a particular
condition is satisfied. The particular condition will be described
in detail in Embodiment 5. In this case, a TRP corresponding to a
particular codeword index, that is, the first or second codeword
may be used as a representative TRP, and a representative TB size
may be calculated from the corresponding codeword.
[0176] In one example of method 3 of DMRS port/port group/CDM group
index, when two or more DMRS ports or CDM groups are used in
repeated transmission, different DMRS ports/port groups/CDM groups
may be used in different TRPs. In this case, a TRP corresponding to
a particular DMRS port/port group/CDM group index, that is, the
lowest/highest DMRS port/port group/CDM group index, may be used as
a representative TRP and a representative TB size may be calculated
from the corresponding codeword.
[0177] In one example of method 4 of frequency resource allocation
information, in repeated transmission, frequency resources of each
repeatedly transmitted codeword may be independently allocated. For
example, a frequency-domain resource allocation (assignment) field
on the NR DCI may be reinterpreted and n frequency-domain resource
allocation (assignment) fields for n codewords may be used.
Alternatively, n-1 frequency-domain resource allocation fields may
be added. In this case, a TRP corresponding to a particular
frequency-domain resource allocation field, that is, the lowest or
highest-order field may be used as a representative TRP, and a
representative TB size may be calculated from the corresponding
codeword.
[0178] In one example of method 5 of frequency/time resource
pattern, frequency/time resources used for each TRP in repeated
transmission may follow a particular pattern. For example, the
frequency/time resource allocated to the codeword transmitted in
the first TRP may be dynamically indicated or quasi-statically
determined through the DCI, and the frequency/time resource
allocated to the codeword transmitted in the second TRP may be
allocated according to a particular offset/pattern based on the
resource of the first TRP. Alternatively, the frequency/time
resources for all TRPs may be dynamically indicated or
quasi-statically determined, and the resource for each TRP may be
distributed according to a particular pattern within the determined
resources. In this case, a TRP corresponding to a particular
pattern order, for example, a TRP transmitting in the lowest RB or
the first symbol/slot, may be used as a representative TRP and a
representative TB size may be calculated from the corresponding
codeword.
[0179] The frequency/time resource pattern may be configured as in
Table 16 described above. In this case, a TRP corresponding to the
even PRG or the odd PRG may be used as a representative TRP, and a
representative TB size may be calculated from the codeword
transmitted by the representative TRP.
[0180] Methods of implicitly configuring the representative TRP are
not limited to the above examples. The above methods may be
operated in combination of two or more as necessary, and there may
be a priority between the methods. For example, when two or more
TCI states are activated, a representative TRP is always determined
according to the TCI state, and when only one TCI state is
activated, a representative TRP may be determined according to the
frequency/time resource pattern of repeated transmission.
[0181] Alternatively, the base station may explicitly indicate the
representative TRP through the DCI/MAC-CE or the like, the terminal
may calculate the representative TB size from the codeword
transmitted in the indicated TRP. An indicator of the
representative TRP may be one of the above-listed information, for
example, an activated TCI state index, a codeword index, or a
combination thereof.
[0182] Meanwhile, a representative LDPC BG may be obtained
similarly to the method of calculating the representative TB size
through the representative TRP.
Embodiment 5: DCI Indication Method for Repeated Transmission
[0183] In the case of repeated transmission through multiple TRPs,
the repeated transmission and the representative TRP may be
configured by the method 2) of Embodiment 4 described above, that
is, by setting the second codeword of the DCI. In this case, the
terminal may need to determine whether two codewords transmitted
are codewords for different data as in the existing NR or codewords
for repeated transmission. In order to determine this, the terminal
may use the following method.
[0184] In one example of method 1, when repeated transmission is
configured in the higher layer, it is determined as repeated
transmission; otherwise, it is determined as different data
transmission.
[0185] In one example of method 2, when multiple TCI states are
activated, it is determined as repeated transmission, and when only
a single TCI state is activated, it is determined as different data
transmission.
[0186] In one example of method 3, when a particular MCS table, for
example, an MCS table 3, is used, it is determined as repeated
transmission; otherwise, it is determined as different data
transmission.
[0187] In one example of method 4, when a particular RNTI, for
example, an MCS-C-RNTI, an RNTI for NC-JT transmission, or an RNTI
for repeated transmission is used, it is determines as repeated
transmission; otherwise, it is determined as different data
transmission.
[0188] A method of determining whether two codewords transmitted by
the terminal are codewords for different data or codewords for
repeated transmission is not limited to the above methods, and
there may be various methods thereof. Also, when it is determined
as repeated transmission, the terminal may not expect that two
codewords transmitted maybe codewords for different data.
[0189] When it is determined as repeated transmission, because the
terminal may not need to calculate the TB size in the codeword for
the TRP other than the representative TRP, the target code rate may
not need to be indicated in the MCS. Thus, in the codeword, the MCS
index used to indicate only a modulation order in retransmission in
the above MCS table may be indicated, or even when the MCS index
used in initial transmission is indicated, the target code rate
information of the index may be ignored and only the modulation
order may be used. Alternatively, a new MCS index indicating only
the modulation order may be used, and because up to four different
modulation orders are indicated in the current NR, two bits may be
required to indicate the corresponding MCS index.
[0190] In this case, currently, the payload for the second codeword
may be redefined. Currently, 5 bits of an MCS field, 1 bit of a new
data indicator (NDI) field, and 2 bits of a redundancy version (RV)
field may be used for the second codeword. However, when only 2
bits are used for the MCS index as described above, an unused
payload may occur and the unused payload may be used to indicate
the third codeword information for repeated transmission. Also,
when the case of retransmitting only a particular TRP among the
TRPs participating in repeated transmission is not considered, the
corresponding payload may be reused because the NDI field of the
second codeword is not used.
[0191] FIG. 14 illustrates an example of redefinition of a DCI
payload in repeated transmission of multiple TRPs in a wireless
communication system according to an embodiment of the disclosure.
Referring to FIG. 14, an example of a method of redefining the DCI
payload for the second codeword is illustrated. In FIG. 14, 14-05
is an example of a method in which a field for the second codeword
of the DCI is redefined to simultaneously indicate the modulation
order and the redundancy version (RV) of the TRPs 2 and 3.
Meanwhile, in repeated transmission, the RV of each codeword may be
semi-statically configured through higher layer configuration. In
FIG. 14, 14-10 is an example of a method in which, when the RV of
each codeword is semi-statically set, a field for the second
codeword of the DCI is redefined to simultaneously indicate the
modulation order of the TRPs 2, 3, 4, and 5.
Embodiment 6: LDPC BG Configuration Method
[0192] Although the TB size transmitted for each TRP in the above
repeated transmission may be equally calculated, the code rate
value calculated according to the target code rate value indicated
by the MCS or the amount of time/frequency resources allocated for
each TRP for repeated transmission may vary. Thus, the LDPC BG
calculated by the terminal may be different for each TRP. In this
case, because the combining of received signals may be difficult as
described above, a method of matching the LDPC BG for each TRP is
presented in the present embodiment of the disclosure as
follows.
[0193] In one example of method 1, when the LDPC BG for each TRP is
different, the terminal may always select a particular LDPC BG
(e.g., BG2). In this case, when there is no or small backhaul delay
time between TRPs and thus information sharing between TRPs is
possible, it may be effective in this case, each TRP may be
scheduled through one piece of DCI. Among the two BGs used in the
LDPC, the BG2 may be used for lower code rates and the BG1 may be
used for relatively high code rates. Meanwhile, because the
reception reliability may increase as the code rate decreases, it
may be convenient in terms of the reliability to assume that the
BG2 is selected when the LDPC BG for each TRP is different.
[0194] In one instance of method 1-1, when the LDPC BG for each TRP
is different, the terminal may select a LDPC BG according to a
certain condition. Among the two LDPC BGs, the maximum length of a
single code block that may be generated for the BG2 is 3840,
whereas that for the BG1 is 8448. Thus, the number of code blocks
may vary depending on which LDPC BG is selected for a particular
TBS, which may affect the reception performance. For example, for a
particular range of code rates, it may be more convenient in terms
of the reliability to transmit the same TB to one code block by
using the BG1 than to transmit the same TB to two code blocks by
using the BG2. Thus, the selected BG may be different according to
a particular condition, for example, a TBS value calculated for
each TRP and/or a code rate for each TRP. For example, when
TBS<=3824, the BG2 may always be selected; otherwise, the BG1
may be selected.
[0195] In one example of method 2, when the LDPC BG for each TRP is
different, the terminal may select a LDPC BG according to higher
layer configuration. Selecting the LDPC BG according to the higher
layer configuration may be effective when there is no backhaul
between TRPs or a long delay time therebetween and thus information
sharing between TRPs is not easy. In this case, each TRP may be
scheduled through different DCI. When the LDPC BG is configured as
the higher layer, the base station and the terminal may expect to
encode/decode the BG selected according to the higher layer
configuration regardless of the TBS and the code rate. According to
the higher layer configuration, one BG, for example, the BG2, may
always be forcibly configured as in the method described in Method
1 and the BG for each TBS range may be configured as in the method
described in method 1-1.
[0196] When the LDPC BG is configured according to the above
method, the maximum length of the code block and the number of code
blocks may be configured according to the corresponding LDPC BG.
When CBG-based transmission is configured in the terminal, as the
number of code blocks used to calculate the CBG is modified, the
number of CBGs used and the method of interpreting the CBGTI field
of the DCI may also be modified. Also, when the terminal uses a
CBG-based HARQ-ACK codebook, the terminal may generate an HARQ-ACK
codebook to correspond to the number of CBGs according to the LDPC
BG configured according to the above method.
[0197] Alternatively, in order not to change the operation of the
existing hardware, a restriction may be configured to calculate the
same number of code blocks in any LDPC BG and the number of code
blocks may be 1. For this purpose, the TBS transmitted for each TRP
and calculated by the terminal may be restricted to a particular
value or less, and the corresponding value may be 3824 that is the
minimum value of the TB length where code block segmentation is
performed in the LDPC BG1 and BG2. By applying the above
constraints, it may be possible to match the LDPC BG for each TRP
without changing operations such as CBG-related retransmission and
HARQ-ACK codebook generation.
[0198] FIG. 15 illustrates a structure of a terminal in a wireless
communication system according to an embodiment of the
disclosure.
[0199] Referring to FIG. 15, the terminal may include a transceiver
15-00, a memory 15-05, and a processor 15-10. The transceiver 15-00
and the processor 15-10 of the terminal may operate according to
the communication method of the terminal described above. However,
the components of the terminal are not limited to the above
example. For example, the terminal may include more components or
fewer components than the above components. In addition, the
transceiver 15-00, the memory 15-05, and the processor 15-10 may be
implemented as a single chip.
[0200] The transceiver 15-00 may exchange signals with the base
station. Here, the signals may include control information and
data. For this purpose, the transceiver 15-00 may include, for
example, an RF transmitter for up-converting and amplifying a
transmitted signal and an RF receiver for low-noise-amplifying and
down-converting a received signal. However, this is merely an
embodiment of the transceiver 15-00, and the components of the
transceiver 15-00 are not limited to the RF transmitter and the RF
receiver.
[0201] Also, the transceiver 15-00 may receive a signal through a
radio channel and output the signal to the processor 15-10 and may
transmit a signal output from the processor 15-10, through a radio
channel.
[0202] The memory 15-05 may store programs and data necessary for
the operation of the terminal. Also, the memory 15-05 may store
control information or data included in the signals
transmitted/received by the terminal. The memory 15-05 may include
a storage medium or a combination of storage media such as ROM,
RAM, hard disk, CD-ROM, and DVD. Also, the memory 15-05 may be
provided in plurality.
[0203] Also, the processor 15-10 may control a series of processes
such that the terminal may operate according to the above
embodiment of the disclosure. For example, the processor 15-10 may
control the components of the terminal to receive the DCI including
two layers to receive a plurality of PDSCHs simultaneously. The
processor 15-10 may be provided in plurality and the processor
15-10 may control the components of the terminal by executing the
programs stored in the memory 15-05.
[0204] FIG. 16 illustrates a structure of a base station in a
wireless communication system according to an embodiment of the
disclosure.
[0205] Referring to FIG. 16, the base station may include a
transceiver 16-00, a memory 16-05, and a processor 16-10. The
transceiver 16-00 and the processor 16-10 of the base station may
operate according to the communication method of the base station
described above. However, the components of the base station are
not limited to the above example. For example, the base station may
include more components or fewer components than the above
components. In addition, the transceiver 16-00, the memory 16-05,
and the processor 16-10 may be implemented as a single chip.
[0206] The transceiver 16-00 may exchange signals with the
terminal. Here, the signals may include control information and
data. For this purpose, the transceiver 16-00 may include, for
example, an RF transmitter for up-converting and amplifying a
transmitted signal and an RF receiver for low-noise-amplifying and
down-converting a received signal. However, this is merely an
embodiment of the transceiver 16-00, and the components of the
transceiver 16-00 are not limited to the RF transmitter and the RF
receiver.
[0207] Also, the transceiver 16-00 may receive a signal through a
radio channel and output the signal to the processor 16-10 and may
transmit a signal output from the processor 16-10, through a radio
channel.
[0208] The memory 16-05 may store programs and data necessary for
the operation of the base station. Also, the memory 16-05 ay store
control information or data included in the signals
transmitted/received by the base station. The memory 16-05 may
include a storage medium or a combination of storage media such as
ROM, RAM, hard disk, CD-ROM, and DVD. Also, the memory 16-05 may be
provided in plurality.
[0209] Also, the processor 16-10 may control a series of processes
such that the base station may operate according to the above
embodiment of the disclosure. For example, the processor 16-10 may
control each component of the base station to configure and
transmit two layers of DCIs including allocation information for a
plurality of PDSCHs. The processor 16-10 may be provided in
plurality and the processor 16-10 may control the components of the
base station by executing the programs stored in the memory
16-05.
[0210] The methods according to the embodiments of the disclosure
described in the specification or the claims may be implemented by
hardware, software, or a combination thereof.
[0211] When the methods are implemented by software, a
computer-readable storage medium may be provided to store one or
more programs (software modules). The one or more programs stored
in the computer-readable storage medium may be configured for
execution by one or more processors in an electronic device. The
one or more programs may include instructions for causing the
electronic device to execute the methods according to the
embodiments of the disclosure described in the specification or the
claims.
[0212] These programs (software modules or software) may be stored
in random access memories (RAMs), nonvolatile memories including
flash memories, read only memories (ROMs), electrically erasable
programmable ROMs (EEPROMs), magnetic disc storage devices, compact
disc-ROMs (CD-ROMs), digital versatile discs (DVDs), other types of
optical storage devices, or magnetic cassettes. Also, the programs
may be stored in a memory configured by a combination of some or
all of such storage devices. Also, each of the memories may be
provided in plurality.
[0213] Also, the programs may be stored in an attachable storage
device that may be accessed through a communication network such as
Internet, Intranet, local area network (LAN), wide LAN (WLAN), or
storage area network (SAN), or through a communication network
configured by a combination thereof. Such a storage device may be
connected through an external port to an apparatus performing an
embodiment of the disclosure. Also, a separate storage device on a
communication network may be connected to an apparatus performing
an embodiment of the disclosure.
[0214] According to the disclosure, when network cooperative
communication is used in a wireless communication system, the
reliability of terminal reception data/control signals may be
improved.
[0215] In the above particular embodiments of the disclosure, the
components included in the disclosure are expressed in the singular
or plural according to the particular embodiments of the
disclosure. However, the singular or plural expressions are
selected suitably according to the presented situations for
convenience of description, the disclosure is not limited to the
singular or plural components, and the components expressed in the
plural may even be configured in the singular or the components
expressed in the singular may even be configured in the plural.
[0216] It should be understood that the embodiments of the
disclosure described herein should be considered in a descriptive
sense only and not for purposes of limitation. That is, it will be
understood by those of ordinary skill in the art that various
changes in form and details may be made in the embodiments of the
disclosure without departing from the scope of the disclosure.
Also, the embodiments of the disclosure may be operated in
combination when necessary. For example, the base station and the
terminal may be operated according to a combination of portions of
an embodiment and another embodiment of the disclosure. For
example, the base station and the terminal may be operated
according to a combination of portions of Embodiment 1 and
Embodiment 2 of the disclosure. Also, although the above
embodiments of the disclosure are presented based on FDD LTE
systems, other modifications based on the technical spirit of the
embodiments of the disclosure may also be implemented in other
systems such as TDD LTE systems and 5G or NR systems.
[0217] Although the present disclosure has been described with
various embodiments, various changes and modifications may be
suggested to one skilled in the art. It is intended that the
present disclosure encompass such changes and modifications as fall
within the scope of the appended claims.
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